Debye Institute for Nanomaterials Science

Debye Institute for 

Nanomaterials Science 

Postgraduate Research Projects 

2011-2012

Contents 

Page 

Introduction 5 

Debye PhD Committee 7 

Postgraduate Research Projects 

Condensed Matter and Interfaces 9 

Inorganic Chemistry and Catalysis 23 

Nanophotonics 75 

Organic Chemistry and Catalysis 93 

Physical and Colloid Chemistry 103 

Soft Condensed Matter and Biophysics 121 

Theoretical Chemistry 151 

Author Index 155 

Techniques Index 161 

Research groups and scientific staff 

3

Introduction 

This book gives an overview of the postgraduate research projects conducted in the various sections 

of the Debye Institute for Nanomaterials Science (DINS) of Utrecht University. With this booklet 

the Debye PhD committee (Debye AIO Commissie – DAC) intends to stimulate collaborations 

between the research groups within the DINS and to document all the research that is being 

conducted. This year there are 103 PhD Students and 32 Postdoctoral researchers who contributed. 

Each person has given a brief description of the main research goals combined with a list of applied 

techniques. In the end of the book two indexes can be found: Author index and Techniques index. 

The Author index gives easy access to the contributions of all postgraduate research projects. The 

updated Techniques index lists all specific scientific techniques of the contributing PhD students 

and Postdoctoral researchers. By providing this list, we hope to stimulate collaborations between 

different fields of expertise. This book is presented during the ‘Debye Spring School’ or during the 

‘DO! Days’ and is also available online: 

http://www.uu.nl/EN/faculties/science/research/researchinstitutes/debye 

On behalf of the Debye PhD Committee, 

Nina Elbers and Arjen van de Glind 

5

Debye PhD Committee 

Dear PhD student, Postdoctoral researcher, 

Welcome to the Debye Institute for Nanomaterials Science (DINS), consisting of research groups 

from the Department of Chemistry and the Department of Physics & Astronomy. The DINS focuses 

on interdisciplinary research, mostly in the field of nanomaterials science. There are about 180 

scientists presently working in the institute along with about 35 supporting staff. 

The Debye PhD committee (Debye AIO Commissie, DAC) was established in order to stimulate 

collaborations between the various groups of the institute and to act as a forum for the postgraduate 

researchers. The committee represents and attends the interests of approximately 103 PhD students 

and 32 Postdoctoral researchers. The DAC also contributes to the educational program of the 

institute, by organizing the ‘Debye Spring School’, the ‘DO! Days’ and company excursions. 

Furthermore, social gatherings are organized such as the Debye Sports Day and BBQ. Last but not 

least, the DAC is also in charge of publishing the annual Postgraduate Research Projects booklet 

which you are reading at the moment. 

In case you have any questions related to the DAC, or you would like to find out more about 

the DAC, the Debye Institute or upcoming events, please contact the DAC representative of your 

group listed below: 

Current DAC members of the participating groups: 

Condensed Matter and Interfaces Esther Groeneveld (secretary) 

Inorganic Chemistry and Catalysis Thomas Eschemann 

Jesper Sattler 

Nanophotonics Diederik Spee 

Organic Chemistry and Catalysis Manuel Basauri Molina 

Physical and Colloid Chemistry Susanne van Berkum (chair) 

Soft Condensed Matter and Biophysics Nina Elbers 

Graduate School of Natural Sciences Arjen van de Glind 

Welcome to our institute and good luck with your research! 

On behalf of the Debye PhD Committee, 

Nina Elbers and Arjen van de Glind 

7

Chemical Biology and Organic Chemistry 

Postgraduate Reserach Projects 

Condensed Matter and Interfaces 

9

10 


Electronic properties at the atomic scale: a STM/AFM study of quantum dots 

and graphene 

Mark Boneschanscher, M.P.Boneschanscher@uu.nl, phone: 030 - 253 35 45 

Sponsor: FOM-FNPS, since November 2009 

Supervisors: Prof. dr. Daniel Vanmaekelbergh and Prof. dr. Peter Liljeroth 

Atomic force microscopy (AFM), Scanning tunnelling microscopy/spectroscopy (STM/STS) 

Scanning probe microscopy allows not only for the visualization of atoms and nanoparticles, but 

more importantly it allows one to choose what properties to visualize. With STM it is possible 

to image the local density of states (LDOS) in real space. This allows for mapping of quantum 

confinement of charge carriers in for example small islands of graphene [1], but it can also be used 

for the visualization of atomic or molecular orbitals. Furthermore it can be used to do energy level 

spectroscopy on for example quantum dots. 

With AFM one studies the forces between tip and sample. This technique can be used for example 

to measure the electron occupation of a single nanoparticle. Another possibility is to pick up a small 

molecule to the tip apex. This functionalized tip can then be used to measure the force between this 

molecule and another one on the surface [2]. Tip functionalization also changes the tip reactivity, 

enabling the use of inert tips. These can be used to measure reactive surfaces in the Pauli repulsion 

regime with strongly increased contrast. This allows for clearly resolving the atomic positions in 

e.g. molecules or graphene. 

Figure 1: A. Comparison of STM and AFM topography on a CO molecule with a CO modified tip. Graph showing the interaction 

potential between the two molecules. B. Energy level spectroscopy on Bi nanocrystals showing the topography and a 

spectrum of the LDOS of one of the nanocrystals. C. Graph of the spatial dependence of the LDOS at different bias inside 

a nanometer sized graphene flake. The atomically resolved graphene flake is measured with a CO tip in AFM. 

[1] S. Hämäläinen, Z. Sun, M.P. Boneschanscher A. Uppstu, M. Ijäs, A. Harju, D. Vanmaekelbergh and P. Liljeroth, Phys. Rev. Lett. 107, 

236803 (2011). 

[2] Z. Sun, M.P. Boneschanscher, I. Swart, D. Vanmaekelbergh and P. Liljeroth, Phys. Rev. Lett., 106, 046104 (2011).


Anisotropic Cd 2+ −for−P b2+ Cation Exchange in PbSe/CdSe: A Route for the 

Synthesis of New Nanomaterials 

Dr. Marianna Casavola, m.casavola@uu.nl, phone: 030 - 253 22 27 

Sponsor: NWO, (CS, Vidi Grant Liljeroth), since September 2011 

Supervisor: Prof. dr. D. Vanmaekelbergh 

Chemical Colloidal Synthesis, Luminescence Spectroscopy, Transmission electron microscopy (TEM) 

Core-shell heterostructured nanocrystals (HNCs) based on semiconductors are an important 

class of optoelectronic materials, which are expected to benefit from the individual properties of 

the single components, and additionally show new features arising from inter-particle quantum 

mechanical coupling. 1 

We present the synthesis of new PbSe/CdSe HNCs, obtained from PbSe nanorods (NRs) by 

partial replacement of Pb with Cd cations (cation exchange). 2-3 A HAADF-STEM study reveals 

that the firstly formed PbSe/CdSe core/shell HNCs evolve in new structures, which consist of 

CdSe (NRs) embedding one or two PbSe NCs each, with dominance of {111} /{111} PbSe CdSe 

interfaces. 3 A combined HAADF-STEM and discrete tomography study allowed us to obtain a 3D 

reconstruction of the PbSe NC core with atomic resolution. 4 This reliable imaging of the heterointerfaces 

sheds light on the reaction mechanism, which can be explained on the basis of the layerby-layer 

replacement of Pb2+ by Cd2+ enabled by a vacancy-assisted cation migration mechanism. 3-4 

Due to their interesting features, like tunable emission in the near-IR and long photoluminescence 

lifetime, these nanostructures hold promise for the development of new devices working in the 

near-IR. In addition, PbSe-based NCs with anisotropic shapes could show emission of polarized 

light in the near-IR, which is advantageous for optoelectronics. Finally we remark that two-dotsin-a-rod 

structures may provide a novel platform for the study of coupling mechanism between 

semiconductor NCs. 

Figure 1: HAADF-STEM pictures of core/shell PbSe/CdSe HNCs with rod- (a) and dot- (b) shaped PbSe core; (c) atomic 

reconstruction of the PbSe core as in (b); (d) schematic showing the vacancy-assisted cation migration mechanism. 

[1] Vanmaekelbergh, D.; Casavola, M. J. Phys. Chem. Lett. 2011, 2, 2024. 

[2] Pietryga J. A. et al. J. Am. Chem. Soc. 2008, 130, 4879. 

[3] Casavola, M.; van Huis, M.A.; Bals, S.; Lambert, K.; Hens, Z.; Vanmaekelbergh, D. Chem. Mater. DOI: 10.1021/cm202796s. 

[4] Bals, S.; Casavola, M.; van Huis, M. A.; Van Aert, S.; Batenburg, K. J.; Van Tendeloo, G.; Vanmaekelbergh, D. Nano Lett. 2011, 11, 3420. 

11

12 


Synthesis and characterization of doped nanoparticles as spectral convertors for 

luminescent solar concentrators 

Joren Eilers, J.J.Eilers@uu.nl, phone: 030 - 253 22 14 

Sponsor: FOM-JSP2, since September 2010 

Supervisors: Prof. dr. Andries Meijerink, dr. Celso de Mello Donegá 

Chemical colloidal synthesis, UV-VIS-NIR absorption spectroscopy, Luminescence spectroscopy, Time resolved laser 

spectroscopy 

Luminescent solar concentrators (LSCs) are a promising solution in the race to produce more 

economical photovoltaic energy. The system, which concentrates spectrally converted sunlight 

on solar cells at the edges of the LSC, greatly reduces the required area of expensive photovoltaic 

cells. Moreover, the ability of LSCs to collect both direct and diffuse sunlight allows the system to 

be used without expensive tracking devices. The main reasons why, at present, LSCs are not being 

used at any significant scale are the low efficiency and limited stability of the current systems. In 

this project we try to address both of these problems. 

Both the efficiency and the stability in the current systems are limited by the dyes used for the 

spectral conversion. It is our goal to develop efficient and stable phosphors that strongly absorb 

photons from incoming sunlight and convert them to a narrow band or line emission in the NIR 

(700-1000 nm) that can efficiently be absorbed by crystalline silicon solar cells. To achieve this goal, 

we investigate a variety of colloidal nanocrystals doped with efficiently luminescing transition metal 

or lanthanide ion activators. The size of the colloidal nanocrystals allows them to be incorporated in 

a LSC polymer without causing scattering. The combination of absorption by a the nanocrystaline 

host or a co-doped sensitizer with energy transfer to the activator ions provides the opportunity 

to minimize re-absorption.

Self assembly of nanocrystals into superlattice solids 

Wiel Evers, w.h.evers@uu.nl, phone: 030 - 253 22 07 

Sponsor: 7th Framework programme, Nanospec 

Supervisors: Prof. dr. Vanmaekelbergh, Prof. dr. Meijerink 

TEM, Electron tomography (3D –TEM), UV-VIS-NIR spectroscopy, Colloidal synthesis 


Formation of binary superlattices (BNSLs) from colloidal nanocrystals (NCs) by self-assembly is a 

promising pathway towards novel materials with unique optoelectronic properties. While a host of 

different superlattice structures and material combinations have been reported, the driving forces 

behind BNSL formation are not fully understood. This information, if available, would be helpful 

in the rational design of nanostructured materials. 

In my research project we investigate driving forces involved in the formation of binary (and ternary) 

superlattices. These superlattices can be composed of semiconductor and/or metallic nanocrystals. 

The main focus up till now has been on superlattices built from semiconductor nanocrystals and 

combinations of semiconductor and metal nanocrystals. The formation of specific crystal structures 

is modeled, in close cooperation with the Soft Condensed matter group, using full free energy 

calculations. In addition, studies on collective opto-electronic phenomena are planned to study 

the interaction between NCs in the superlattices. For instance, in a binary superlattice of CdSe 

and PbSe coupling between the two types of NCs may result in a type II band structure. In the 

figure below three different binary superlattices composed of PbSe and CdSe NCs are shown. The 

binary superlattices were obtained for different size ratio’s (y) of the NCs. From left to right crystal 

structures with AlB , NaZn and MgZn stoichiometry are shown. 

2 13 2 

Besides studying the collective properties of the binary superlattices, it is vital to understand the 

optical properties of the separate building blocks. While in literature PbSe and CdSe are widely 

investigated, the core|shell particle PbSe|CdSe is less characterized. In my research I also investigate 

the optical properties of PbSe|CdSe NCs. In addition, I investigate the influence of different shell 

materials on the core|shell particle to improve the photoluminescence quantum yield and the 

stability of the nanocrystals. 

Figure 1: Binary superlattices obtained for different size ratio’s. From left to right AlB 2 , NaZn 13 and MgZn 2 stoichiometries 

are shown. 

13

14 


Structural characterization and opto-electronic properties of PbSe/CdSe 

heteronanocrystals 

Dominika Grodzinska, D.Grodzinska@uu.nl, phone: 030 - 253 23 21 

Sponsor: EU (Marie Curie HERODOT) 

Supervisors: Prof. dr. Daniel Vanmaekelbergh, Prof. dr. Celso de Mello Donegà 

UV-Vis-NIR spectroscopy, Time resolved laser spectroscopy, (STM/STS) 

PbSe/CdSe HNCs have attracted increasing attention over the past decade due to their optical 

properties in the near- and mid-infrared spectral range.[1, 2] CdSe crystallizes in the wurtzite (WZ) 

or zinc-blende (ZB) structure and has a low refractive index (2.6), while PbSe has a rock-salt (RS) 

crystal structure and a high refractive index (4.7). The difference in the coordination numbers of 

the atoms in the two types of crystal structure precludes interdiffusion and makes CdSe ZB and 

PbSe RS immiscible. In combination with a very small lattice mismatch (~1%), this leads to an 

atomically sharp PbSe/CdSe heterointerface, consisting of a Se (111) plane. 

The research project is focused on the preparation of colloidal PbSe/CdSe core/shell QDs and their 

new remarkable atomic reconstruction upon the thermall annealing in vacuum into PbSe/CdSe 

bi-hemisphere HNCs (see figure below)[3], and also on their optical and electronic characterization 

before and after heating. Applications can be related to electron-hole charge separation in solar 

cells, lasing and ordered electronic doping. 

[1] Pietryga, J.M., Werder, D.J., Williams, D.J., Casson, J.L., Schaller, R.D., and Klimov, V.I., Utilizing the Lability of Lead Selenide to 

Produce Heterostructured Nanocrystals with Bright, Stable Infrared Emission. Journal of the American Chemical Society, 2008. 

130(14): p. 4879-4885. 

[2] Sholin, V., Breeze, A.J., Anderson, I.E., Sahoo, Y., Reddy, D., and Carter, S.A., All-inorganic CdSe/PbSe nanoparticle solar cells. Solar 

Energy Materials and Solar Cells, 2008. 92(12): p. 1706-1711. 

[3] Grodzinska, D., Pietra, F., van Huis, M.A., Vanmaekelbergh, D., and de Mello Donega, C., Thermally induced atomic reconstruction 

of PbSe/CdSe core/shell quantum dots into PbSe/CdSe bi-hemisphere hetero-nanocrystals. Journal of Materials Chemistry, 2011. 

21(31): p. 11556-11565.


Synthesis and Photophysical Properties of Colloidal Type-II Heteronanocrystals 

Esther Groeneveld, E.Groeneveld@uu.nl, phone: 030 - 253 22 07 

Sponsor: Utrecht University, since October 2008 

Supervisors: Dr C. de Mello Donegá, Prof. dr. A Meijerink 

UV-VIS-NIR Spectroscopy, Luminescence spectroscopy, Time resolved laser spectroscopy, Transmission electron 

microscopy (TEM) 

Colloidal semiconductor nanocrystals (NCs) have, as a result of quantum confinement effects, size 

dependent properties (e.g., energy levels change as function of size, figure 1A) which makes them, 

along with their convenient fabrication method, promising materials for various applications, such 

as LEDs, solar concentrators, solar cells, and biolabels. In a semiconductor heteronanocrystal (HNC) 

two semiconductor materials are combined in a single particle. Compared to single component 

NCs, HNCs exhibit even more complex properties. In these heterostructures the charge carrier 

localization after photo-excitation can vary. This localization depends on the energy offsets between 

the valence and conduction band levels of the materials that are combined at the heterointerface. 

The relative energy offsets between the conduction and valence bands can be tuned by varying the 

size, shape, and composition of the components of the HNC. Three different classes of HNCs can 

be distinguished based on the carrier localization, namely Type I, Type I1/2 , and Type II. A schematic 

overview of the three types is given in figure 1B. The control of the localization regime offers the 

possibility of tuning the electron-hole wavefunction overlap, thereby tailoring the optoelectronic 

properties of the HNC. This has important consequences for a number of technologies, and opens 

up interesting application possibilities, e.g.: photovoltaic devices, solar concentrators, and fast optical 

switches. 

The aim of this project is to synthesize colloidal Type-II HNCs and investigate their photophysical 

properties, e.g. CdTe/CdSe, and ZnSe/CdSe. HNCs are synthesized via a multistage seeded growth 

approach, in which high-quality cores are essential to obtain high-quality HNCs. Since size and 

shape of the HNCs are important, in addition to full optical characterization also full structural 

characterization of the HNCs is needed. The optical properties of the HNCs are studied as function 

of composition and temperature. 

15

16 


Self-Absorption in Quantum Dot based Luminescent Solar Concentrators 

Zachar Krumer, Z.Krumer@uu.nl, phone: 030 - 253 35 45 

Sponsor: FOM since April 2010 

Supervisors: Prof. dr. R.E.I. Schropp, Prof. dr. C. Mello-Donega and dr. W.G.J.H.M. van Sark 

Luminescence spectroscopy, Time resolved laser spectroscopy 

The approach of luminescent solar concentrators (LSCs) aims at reducing the use of semiconducting 

material in solar cells by optical concentration. The LSC consists of a highly transparent low-cost 

polymer plate, in which quantum dots are dispersed. The incident photons from any direction are 

absorbed by the quantum dots and red shifted photons are subsequently emitted, with high quantum 

efficiency. This light is trapped by total internal reflections and directed to a thin film silicon solar cell, 

which converts the photon energy into electrical energy. This concept allows diffuse light concentration 

at the expense of spectral energy. 

The efficiency of LSCs is still low, due to self-absorption of the emitted light by the fluorescent 

material. This project compares the self-absorption behaviour of different luminescent species. To do 

so a method for evaluation of this phenomenon has been developed. The measurements are carried 

out on a solution based prototype, which does not require the fabrication of a new concentrator 

plate for each different luminescent species and therefore allows for a fast and convenient screening 

of potentially interesting luminophores. So far semiconductor heteronanocrystals of Type II and Type 

I ½ have shown the least pronounced self-absorption effects and hold thus promise as materials for 

efficient LSCs.


Development of new upconversion materials to increase the efficiency of 

solar cells 

Dr. Rosa Martín-Rodríguez, R.MartinRodriguez@uu.nl, phone: 030 - 253 22 07 

Sponsor: NanoSpec, since April 2011 

Supervisor: Prof. dr. Andries Meijerink 

Luminescence spectroscopy, Time resolved laser spectroscopy, UV-Vis-NIR spectroscopy 

In solar cells a large fraction of the incident solar energy is lost because the energy of photons exceeds 

the bandgap, and excess energy is lost by thermalization. In addition, further energy is also lost due 

to photons with energy below the bandgap, which are not absorbed by the solar cell [1]. Photon 

upconversion (UC) processes, in which higher energy light is obtained after the absorption of two or 

more lower-energy photons, is a promising approach to reduce energy loss for sub-bandgap photons. 

An upconverting layer mounted beneath a bifacial solar cell can increase the maximum theoretical 

efficiency up to ca. 47% for a c-Si solar cell for un-concentrated terrestrial solar spectrum (AM1.5) [2]. 

The general aim of the NanoSpec European project in which we are involved is the development of 

new materials for harvesting sub-bandgap photons by UC processes in order to increase solar cells 

efficiencies. Insulating materials doped with rare-earth (RE) ions are very suitable for this purpose. 

In particular, my project is focused on the optimization of the upconverting material by changing 

the host lattice or comparing different combinations and concentrations of RE impurities. Contrary 

to near-infrared to visible UC luminescence in which NaYF : Er 4 3+ , Yb 3+ has been shown to be the 

most efficient material, we have demonstrated that other host materials such as Y O S present higher 

2 2 

efficiencies for infrared to near-infrared UC, after excitation into the 4I Er 13/2 3+ level around 1.5 μm. 

Besides, Ho3+ is also a very interesting ion for spectral conversion since the excitation in the 5I and 7 5I6 levels absorbs a region of the solar spectrum transparent to silicon solar cells, around 2 and 1.15 μm. 

Moreover, co-doping with Yb3+ ions is another interesting approach, since efficient energy transfer 

has been demonstrated from Er3+ or Ho3+ ions to Yb3+ ions, and the 2F � 5/2 2F Yb 7/2 3+ emission can 

also be absorbed by silicon solar cells. 

[1] B. M. van der Ende, L. Aarts, A. Meijerink, Phys. Chem. Chem. Phys. 11 (2009) 11081. 

[2] T. Trupke, M.A. Green, P. Würfel, J. Appl. Phys. 92 (7) (2002) 4117. 

17

18 


Infrared Colloidal Quantum Dots for Photovoltaics 

Dr. Dariusz Mitoraj, D.Mitoraj@uu.nl, phone: 030 - 253 22 14 

Sponsor: FOM, since June 2010 

Supervisor: Prof. dr. Daniël A.M. Vanmaekelbergh 

TEM, UV-Vis spectroscopy, Ultrafast pump-probe 

Single-junction Colloidal Quantum Dots Solar Cells are realized as (i) Schottky, so called (ii) Depleted 

Heterojunction, (iii) Deplated Bulk Heterojunction and (iv) Quantum Dot-Sensitized devices. The 

active, light absorbing Quantum Dot layer is usually sandwiched between Transparent Conductive 

Oxide (ITO, FTO) and back electrode: Al, Ag, Au, Ni, Ca, Mg, LiF, BiCl , MoO , NiS. The high 

3 3 

absorption coefficient of Quantum Dots (typically lead chalcogenide) enable the absorption of visible 

and a significant part of the infrared light for material of thickness ca. 1 μm. However, the diffusion 

length of minority carriers (electrons) for Schottky devices was reported to be considerably lower (tens 

of nm). Thus, a considerable fraction of the photo generated carriers cannot be collected. A higher 

quantum yield will require larger mobilities (above 0.1 cm2 /Vs) and a reduction of the electron-hole 

recombination rate. Moreover, carrier recombination caused by the mid-gap states limits carrier 

lifetime to nanosecond and below. Excellent passivation of quantum dot surface is neccesery to lower 

trap energy depth and density. According to prediction, decrease in trap energy depth from 0.25 to 

0.22 eV and in trap densities from 5×1014 to 9×1013 while increasing charge carriers mobilities from 

0.03 to 0.1 cm2 /Vs should benefit in power efficiency from 6% (record reported efficiency of PbS 

passivated by atomic ligands -based device) to 10%. 

This project is focused on improving the power conversion efficiency by (i) a better design the 

architecture of solar cell device i.e. by improving the carrier tunneling between the quantum dots, (ii) 

increasing diffusion length, lifetime and mobility of the carrier in the active solid film by exchanging 

the original isolating, capping ligands into short organic or inorganic, and (iii) reducing the carrier 

recombination rate by passivating the electrical contacts by using designed electron or hole conductive 

intermediate layers. 

[1] Tang J. et al., Advanced Materials, 2011, 23, 12-29.


Synthesis, self-assembly and photophysical properties of colloidal heteronano 

structures 

Francesca Pietra, F.Pietra@uu.nl, phone: 030 - 253 22 27 

Sponsor: EU(Marie Curie HERODOT), since August 2010 

Supervisors: Prof. dr Daniel Vanmaekelbergh, dr. Celso de Mello Donegá 

TEM, Luminescence spectroscopy, time-resolved laser spectroscopy, Grazing Incidence Small Angle X-Ray 

Scattering (GISAX) 

The ability to manipulate the chemical and physical properties of anisotropic colloidal nanocrystals 

(for instance heteronano rods) at the atomic level, together with the ability to assemble them into 

ordered 2-D membranes and 3-D solids, is certainly one of the most fascinating and challenging 

aspects of current nanoscience. Colloidal inorganic heteronanocrystals (HNCs) combine -in one 

colloidal particle- disparate materials that enhance the functionality of the system. These structures 

have been exploited as the novel building blocks of matter. In this sense the spontaneous organization 

of HNCs in ordered membranes -in which the rods are hexagonally packed- enables the fabrications 

of new classes of materials who could show novel collective properties that can be controlled 

by the periodicities of the assembly, as well by the dimensions and composition of individual 

heteronanocrystals. Nanorods membranes hold promise for collective optical properties that arise 

from quantum mechanical or dipolar interactions between the rod building blocks. For this reasons, 

nanocrystal superlattices and membranes are increasingly being exploited as the active elements of 

optoelectronic devices as LEDs, lasers and solar cells. 

My project is focused on the study of semiconductor heteronanostructures, in particular on CdSe/ 

CdS dot in rod systems and metal(Pt)/semiconductor heteronanocrystals with a particular emphasis 

put on the investigation of their photophysical and photcatalytic properties. Also the spontaneous 

self assembly process has been monitored using X-ray techniques, in order to study the mechanism 

of the nanorod self assembly at the liquid-air interface. In addition the intriguing optical properties 

of these CdSe/CdS nanorods membrames with and without direct magnetic field are currently 

explored. 

Figure 1: TEM images of large vertically oriented nanorod domains. 

19

20 


Hybrid nanoscale structures 

Freddy Rabouw, F.T.Rabouw@uu.nl, phone: 030 – 253 22 03 

Sponsor: FOM, since September 2011 

Supervisors: Prof. dr. D.A.M. Vanmaekelbergh and Prof. dr. A. Meijerink 

(Time-resolved) photoluminescence spectroscopy, transmission electron microscopy, x-ray diffraction 

Quantum dots are interesting for solar cell applications due to the size-tunable optical properties 

and the solution processability. Recently, quantum dot solar cells with a power conversion efficiency 

of 6% have been reported [1]. The main factor limiting the efficiency is recombination of excited 

charge-carriers: before separation of the initially created electron-hole pair, via defect or surface 

states on the quantum dots, or at the electrodes. 

In this project we will work with hybrid structures, that can have superior properties over simple 

quantum dots. These can be either semiconductor-semiconductor structures or semiconductormetal 

structures. Semiconductor-semiconductor structures include heteronanocrystals in which 

the heterointerface facilitates electron-hole separation. One of the structures of interest are CdSe/ 

CdS dot-in-rods. In semiconductor-metal structures surface plasmon resonances in the metal can 

enhance the excitation rate of quantum dots or the energy transfer rate between them. One of the 

structures of interest are quantum dots coated with a gold shell. 

We will study and seek to optimize the optical and electronic properties of these structures. In 

addition, we will investigate the (self-)assembly. 

[1] J. Tang, E.H. Sargent et al., Colloidal-quantum-dot photovoltaics using atomic-ligand passivation, Nature Materials 2011, 10, 

765-771.

ZnO nanowire lasers 

Dr. (Lam)Bert van Vugt, L.K.vanVugt@uu.nl, phone: 030 - 253 44 61 

Sponsor: Nanonextnl, since October 2011 

Supervisor: Prof. dr. Daniël Vanmaekelbergh 


Organometallic synthesis, Luminescence spectroscopy, Focused ion beam, Fluorescence microscopy 

The goal of this project is to demonstrate electrically driven ZnO based nanolasers with low power 

requirements. Due to its high exciton binding energy of 60 meV, bandgap of 3.3 eV, low cost, 

bio compatibility and friendliness to the environment, nanolasers made of ZnO form attractive 

candidates for applications in (bio)sensing, optical computing, white light emission and high density 

storage. This project presents major challenges in the fields of semiconductor synthesis and doping, 

as well as in the area of optical nanocavity formation. These challenges will be met by using novel 

liquid injection MOCVD methods for the highly controlled synthesis and doping of ZnO nanowires 

and thin films. ZnO nanowire crystals naturally form Fabry-Pérot and whispering gallery optical 

cavities whereas suitable optical resonators can be made from thin films by consecutive lithography 

and focussed ion beam (FIB) etch steps. Intrawire P-n junctions enabling electrical injection will 

be formed by either impurity or electrostatic doping. Characterization of as grown wires entail 

spatially resolved single wire optical measurements such as excitation spectroscopy and spectrally 

resolved Fourier microscopy, as well as optical measurements in the presence of on-chip applied 

fields. These measurements provide critical information on light-matter coupling and polaritonic 

effects in these systems that can guide cavity optimization and could potentially elucidate novel 

gain mechanisms such as polariton lasing. 

Figure 1: Photograph of the laser emission from an optically pumped ZnO nanowire (∅200 nm, length 4µm). The interference 

pattern is caused by the coherently emitted light from both ends of the nanowire which acts as a fabry-Pérot optical cavity. 

21

22 


Synthesis, optical properties and bio-applications of luminescent nanoparticles 

Yiming Zhao, Y.M.Zhao@uu.nl, phone: 030 - 253 23 21 

Sponsor: NOW-CW, since February 2009 

Supervisors: Prof. dr. Andries Meijerink, dr. Celso de Mello Donegá, and dr. Willem Mulder 

Luminescence spectroscopy, Time resolved laser spectroscopy, Transmission electron microscopy (TEM), 

Single particle spectroscopy 

The increasing demand for novel, functional, nano-sized material inducts the research on luminescent 

materials shifting toward the nanoscale. The development of luminescent nanoparticles has led 

to a wealth of new applications in many fields, most notably in biology, in areas such as cell 

tracing, molecular imaging and micro-environmental sensing etc. My project focus on developing 

new luminescent nanoparticles (including semiconductor quantum dots and lanthanides doped 

nanocrystals), incorporating them into bio-compatible structures and applying them in the field 

of molecular imaging. 

Introducing dopants into nanocrystals offers the possibility to add specific functionalities (such 

as optical or magnetic properties). In my current research, the synthesis and optical properties 

of lanthanide doped semiconductor or insulator nanocrystals are studied. A new single-source 

precursor method was developed to make the host material: nearly monodispersed CaS/SrS colloidal 

nanocrystals, and this method also enable the possibility of doping with a wide range of metal ions, 

such as Ce3+ , Eu 2+ and Bi3+ .(see Figure) Base on this, many new types of doped nanocrystals can 

be synthesized, which enables searching of new phenomena. Potential application is also under 

investigation: such as afterglow nanoprobes for bio-imaging, luminescent solar concentrator or 

spectral conversions for white light LEDs. 

Figure 1: (a) TEM image of SrS nanocrystals prepared by thermal decomposition of strontium(diisopropyldithiocarbama 

te) stabilized by oleic acid. Insert: electron diffraction pattern with indicated reflections. (b)Emission spectra of SrS:Ce3+ nanoparticles with different dopant concentration excited at 430nm.

Chemical Biology and Organic Chemistry 


Inorganic Chemistry and Catalysis 

23

24 


Catalytic Production of Butadiene from Bio-ethanol 

Carlo Angelici, C.Angelici@uu.nl, phone: 06 – 22736372 

Sponsor: CatchBio, since September 2010 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen and dr. Pieter C.A. Bruijnincx 

Catalyst preparation, N 2 -physisorption, GC, UV-Vis, XRD 

The amount of bio-ethanol produced is increasing yearly, mainly for its use in fuels or as a fuel 

additive (Figure 1). Furthermore, due to its various uses in chemical synthesis it is a key chemical 

for industrially relevant applications. 

Figure 1: Ethanol production in millions of liters in the past decades. 

1,3-Butadiene is an important monomer in polymer chemistry, used for the production of e.g. 

polybutadiene, ABS (Acrylonitrile-Butadiene-Styrene) and SBR (Styrene-Butadiene-Rubber), the 

main component of car tires. 

Currently, butadiene is obtained by steam cracking of fossil hydrocarbons. More sustainable ways of 

producing butadiene from renewable resources is clearly desired. The Lebedev process is considered 

an important and environmentally friendly alternative synthetic way to produce butadiene [1]; this 

old process, known since the first half of the twentieth century, consists in the reaction of two ethanol 

molecules to give the desired product, two molecules of water and one of hydrogen (Scheme). The 

recent increase in bioethanol availability if coupled with improvements in the catalyst can make 

this route an attractive alternative for butadiene production. 

Scheme 1: Overall reaction observed in the Lebedev process. 

The development of a catalytic system able to selectively produce butadiene is of crucial importance 

for this project. On the other hand, the understanding of the mechanism is critical in this research 

study, taking into account the ones already proposed in literature. 

[1] Appl. Catal. 43, 1988, 117.


Influence of Steaming on the State of Aluminum and Methanol-to- 

Hydrocarbon Conversion over Zeolite Catalysts 

Luis R. Aramburo Corrales, L.R.Aramburocorrales@uu.nl Phone: 06 - 22736364 

Sponsor: NRSC-C, since November 2008 

Supervisor: Prof. dr. ir. Bert M. Weckhuysen 

STXM, IR, UV-Vis, CFM 

Zeolite materials have widespread applications as heterogeneous catalysts in chemical industry due to 

their acidic and porosity properties. Specific framework topologies combined with Brønsted acidity 

allow the performance of shape selective catalysis, which increases the cost-effectiveness of chemical 

processes. To further boost the catalytic activity and/or selectivity, the properties of zeolites can be 

adjusted and large efforts have been made to control and hierarchically modify them during their 

synthesis or via different post-treatments. Among them, dealumination via steaming has become a 

cheap and efficient way to alter the topological and acidic properties of zeolites. Nevertheless, to 

further optimize their properties, an in-depth understanding of the physicochemical processes that 

determine the catalytic properties of zeolites is needed. 

To study the changes in zeolite properties during steaming and how these render into their catalytic 

performance, the combination of in-situ spectroscopic techniques, operating at different length 

scales, is required. In this way, the “global” and “local” behavior of zeolite materials can be revealed 

under reaction conditions and correlated to the alterations in the catalyst properties with great 

detail. Specifically, this methodology is applied to thoroughly study the coke formation process on 

the Methanol-To-Hydrocarbon (MTH) process, as a result of the rising necessity to develop new 

technologies based on alternative resources. 

Complementarily, to further understand the intrinsic reactivity and diffusion properties of zeolite 

materials, the use of model systems is of assistance. Thanks to their large dimensions, the compromise 

between chemical information and spatial resolution (often faced by most of the spectroscopic 

techniques) is minimized, obtaining valuable new information on these systems. 

Figure 1: (a) Microphotographs and (b) UV-Vis spectra of parent (top) and steamed (bottom) coffin-shape ZSM-5 crystals 

during the course of MTH at 500°C. Carbon K-edge x ray absorption spectra (XAS) obtained from the MTH reaction performed 

over parent (c) and steamed (d) commercial ZSM-5 zeolites. Spatial distribution of the distinct carbon XAS present within 

a single aggregate in parent (b) and steamed (d) ZSM-5 zeolites. The scale bar represents 250 nm in both cases. 

25

26 


Improved hydrogen sorption kinetics in supported Mg 2 Cu nano-particles 

Yuen Au, y.s.au@uu.nl, phone: 06 - 22736385 

Sponsor: NWO-VIDI (016.072.316), since March 2010 

Supervisors: Prof. dr. ir. Krijn P. de Jong and dr. Petra E. de Jongh 

XRD, TPD/TPR, N 2 -Physisorption, SEM 

Reversible hydrogen storage in metal hydrides is favorable with regard to safety and volumetric 

storage density. The Mg Cu-H system can reversibly store hydrogen following the reaction: 

2 

2 Mg 2 Cu + 3 H 2 ↔ 3 MgH 2 + MgCu 2 

The equilibrium temperature for H -sorption in this system is 240 °C at 1 bar H . Nano-sizing and 

2 2 

confinement improve the kinetics and reversibility of hydrogen sorption reactions in light metal 

hydrides.[1] We investigated the hydrogen release and reversibility for different carbon-Mg Cu 2 

nanocomposites. 

Mg Cu species were prepared on porous and non-porous graphitic carbon supports. We first 

2 

impregnated the carbon with a Cu(NO ) solution. After decomposition of the nitrate and reduction, 

3 2 

supported metallic Cu particles were obtained. Mg Cu was formed by adding MgH to the Cu- 

2 2 

carbon composition and heating the mixture to the melting temperature of Mg. The smallest 

crystallites were obtained with porous carbon (a) with an average size of 50 nm according to 

XRD. SEM, performed in BSE mode, confirmed the presence of the small crystallites. The sample 

prepared on graphite (b) yielded significant larger crystallites (>200 nm). Sample a prepared on 

porous carbon released hydrogen at much lower temperatures than the other samples. This is likely 

due to the decrease in diffusion distance for hydrogen and/or increased specific surface area of the 

Mg-Cu crystallites. Results from cycling experiments performed gravimetrically showed that the 

improved desorption kinetics were maintained. 

Figure 1: TPD, Sample (a) shows the fastest kinetics for 

hydrogen release compared to (b) an analogue prepared 

on non-porous carbon and (c) a physical mixture of the bulk 

material mixed with porous carbon. 

[1] ChemSusChem 3, 2010, 1332. 

Figure 2: SEM, (a) Small Mg Cu particles with an 

2 

average size of 50 nm was observed (b). Much 

larger particles are observed when non-porous

Highly active and stable methanol synthesis catalysts 

Roy van den Berg, R.vandenberg1@uu.nl, phone: 06 - 22736385 

Sponsor: Haldor Topsøe A/S, since December 2011 

Supervisors: Prof. dr. ir. Krijn P. de Jong and dr. Petra de Jongh 

3D-TEM, TEM, Inorganic Synthesis, Catalytic Testing 


The synthesis of methanol from a mixture of CO, CO 2 and H 2 is a highly valuable process. The 

synthesized methanol can be used in the methanol to olefins (MTO) synthesis. [1] In turn, these 

olefins can be used to produce polymers and related products. Methanol is furthermore used as 

the principal feedstock for the production of many other organic compounds, like formaldehyde, 

acetic acid, MMA, DMT and MTBE. [2] Another application of the methanol synthesis is the 

storage of energy by converting H into methanol. The energy density per volume is much 

2 

higher for methanol compared to H and methanol is far easier to store and distribute. [1] The 

2 

methanol economy might thus be an interesting alternative for the hydrogen economy. A potential 

application of the methanol synthesis is the conversion of CO , in order to storage energy rather 

2 

than to mitigate greenhouse gases. 

The goal of this research is to synthesize highly active and stable copper-based methanol synthesis 

catalysts [3] and to get a fundamental understanding of the preparation processes and characteristics 

of the final catalysts. The activity of the catalysts will be tested at industrial conditions. The catalysts 

will be characterized using electron tomography (3D-TEM) and in-situ TEM. [4] In-situ TEM 

will be used to characterize the catalysts during conditions that mimic methanol synthesis. Figure 

1 shows a prime example of this technique where it is seen that copper nanoparticles dynamically 

change their shape upon variation of the gas environment. 

Figure 1: Dynamic shape changes of cupper methanol synthesis catalysts upon gas environment determined via in-situ 

high resolution TEM.[4] 

[1] Angew. Chem. 44, 2005, 2636. 

[2] T.M., Phys.Chem. 6, 2004, 4522. 

[3] J. Phys. Chem. C, 115, 2011, 14698. 

[4] P.L., Adv. Catal. 50, 2006, 77. 

27

28 


Surface Chemistry and Spectroscopy of Phosphorous- Modified Zeolite 

Materials 

Hendrik van der Bij, H.E.vanderbij@uu.nl, phone: 06 - 22736385 

Sponsor: Total, since May 2010 


FT-IR, UV-Vis, NMR, STXM 

Zeolites are crystalline aluminosilicates, which are an important class of molecular sieves. They are 

readily used in industry, in adsorption and separation processes as well in shape selective catalysis. 

The main fields in which zeolites are used as solid-acid catalyst materials are oil refining and 

basic petrochemistry. Many of these catalytic processes are performed under severe hydrothermal 

conditions. In these conditions, dealumination of zeolite materials is favored. Dealumination leads 

to rapid catalyst deactivation. Therefore, it is of paramount importance that zeolites used in these 

processes are hydrothermally stable or stabilized. 

To prevent permanent deactivation, modification of zeolites by addition of phosphorous has proven 

to be an effective route to provide hydrothermal stability. After phosphorous introduction and 

subsequent calcination there are several counter-producing effects. On the one hand there is a 

reversible decrease in activity due to the interaction of phosphorous species with protonic sites, 

there is a decrease in surface area and micropore volume due to blockage by phosphorous species 

and, to a certain degree, dealumination. On the other hand, phosphorous-modified zeolites retain 

their acidity and activity to a significant higher degree than their non-treated counterpart after 

steam treatment and allow an enhanced temperature range for catalytic applications. This suggests 

that specific phosphorous species formed reinforce the zeolite structure and prevent dealumination. 

During the course of this research, a combination of spectroscopic techniques will be used to 

follow different preparation routes of phosphorous-modified zeolite materials both in-situ and 

ex-situ. Ultimately we hope to gain fundamental insight in the structure-performance relationship 

of phosphorous-modified zeolites. 

Figure 1: Multi-pronged approach on phosphorous-modified zeolite materials: a) H-ZSM-5 b) H-ZSM-5 with 2 wt.% P c) 

H-ZSM-5 with 2 wt.% P, hydrothermally treated. Left – 27Al MAS NMR, inset is 2D 27Al MQ MAS NMR. 1 = Al(IV) framework. 

2 = Distorted Al(IV). 3, 4 = Al(VI). Center – X-ray absorption spectra of Al K-edge. I = Al(IV) II = Al(VI). Right – Chemical 

map showing a cluster of particles from H-ZSM-5 2 wt.% P, constructed from the Al K-edge spectra.


Renewable H 2 Production via Aqueous-Phase Reforming of Biomass-Derived 

Oxygenates 

Dilek Ayse Boga, D.A.Boga@uu.nl, phone: 06 - 22736361 

Sponsor: SK Energy, since February 2009 


XRD, TEM, XAFS, ATR-IR 

The decrease of fossil fuel reserves in combination with the continuous increase in energy demand 

has turned the attention of scientists to alternative energy sources. In this manner, renewable fuels 

generated from biomass have become the centre of interest. Biomass is practically the only sustainable 

source for the production of renewable energy and fuels. In addition to its heavy use as a reactant 

in the (petro-) chemical industry, hydrogen has been projected to be one of the few long-term 

sustainable clean energy carriers. A potential strategy for hydrogen production is to convert biomassderived 

intermediates (e.g. glycerol, sorbitol, glucose) via catalytic reforming, which can be done by 

catalytic aqueous-phase reforming (APR) or steam reforming of the biomass-derived oxygenates. 

Hydrogen production by APR of biomass-derived oxygenates has several advantages over steam 

reforming process, including diminished energy requirement (by eliminating the vaporization 

of water and oxygenate), eliminated undesirable decomposition reactions which are typically 

encountered at elevated temperatures (by proceeding at low temperatures) and the possibility 

of performing the reaction in a single-step process in contrast to multi-reactor steam reforming 

system. The production of hydrogen by aqueous phase reforming of oxygenated hydrocarbons over 

supported metal catalysts comes with significant challenges with regards to selectivity. The products 

CO and H are unstable at low temperatures and readily give alkane and water by Fischer-Tropsch 

2 2 

and methanation reactions. Therefore, hydrogen selectivity plays a role of utmost importance in the 

APR of oxygenated hydrocarbons. The aim of this project is to study hydrogen generation from 

low temperature reforming of oxygenated hydrocarbons derived from biomass. 

29

30 


Melt Infiltration of Porous Matrices with Light Metals, Alloys or Hydrides to 

prepare Nanostructured Materials for Energy Storage 

Dr. Christina Bossa, C.Bossa@uu.nl, phone: 06 - 22736090 

Sponsor: ACTS Sustainable Hydrogen Programme, since October 2011 

Supervisor: Dr. Petra E. de Jongh 

Inorganic synthesis, DSC, N 2 -physisorption 

For the advancement of hydrogen based energy technology, efficient and compact hydrogen storage 

systems need to be developed. One of the most promising options is the storage of hydrogen in 

form of metal hydrides. However, at the moment, no known material meets all specifications in 

terms of gravimetric hydrogen capacity, release, uptake kinetics, reversibility and thermodynamics. 

Recently, it was shown that nano-confinement of metal hydrides in porous carbon matrix had a large 

positive effect on both kinetics and thermodynamics of hydrogen uptake and release. Methods to 

prepare confined materials are for example ball milling, solution impregnation and melt infiltration. 

For the latter, no solvent is necessary and high loadings inside the porous matrix can be achieved. 

The technique and principles of melt infiltration are studied. The main focus is on the preparation 

of composite materials for hydrogen storage. Relevant battery electrode materials will also be 

investigated. Initial experiments are carried out on Mg-based and B-based materials. Li-Si and Li-Sn 

systems will also be of interest. The factors which determine the scope of the materials for which 

the technique can be applied are studied. For example, surface and interfacial energies, melting 

points, wettability, etc. affect the outcome of melt infiltration. Differential scanning calorimetry is 

applied as main experimental method.


Investigation of Fluid Catalytic Cracking Catalyst Particles by Micro-Spectroscopy: 

Acidity and Structure 

Dr. Inge Buurmans, I.L.C.Buurmans@uu.nl, phone: 06 - 22736365 

Sponsor: Albemarle Catal-ysts BV, since October 2007 


UV-Vis spectroscopy, confocal fluorescence microscopy, integrated laser & electron microscopy (iLEM) 

Fluid Catalytic Cracking (FCC) is a very important industrial process for the production of 

transportation fuels and chemicals from oil fractions. The spherical FCC catalyst particles (Ø 70 

μm) contain a zeolite and several matrix components (e.g., clay, silica and alumina). The acidity of 

the individual catalyst components and their accessibility towards reactants is very important for 

the activity of the catalyst since cracking is initiated by the protonation of oil molecules in the 

catalyst bodies. 

In this study we present a new approach to investigate such catalyst particles at the individual particle 

level with both light microscopy and electron microscopy techniques. By combining confocal 

fluorescence microscopy with the Brønsted acid-catalyzed oligomerization of styrenes or thiophenes 

as probe reactions, visualization of the Brønsted acidic zeolite component of an individual catalyst 

particle is enabled, as depicted in Figure 1 for fresh (a) and three types of laboratory deactivated 

catalyst particles (b, c, d). A clear decrease in fluorescence intensity and thus reactivity of the zeolite 

domains is observed upon deactivation [1]. Detailed information on the acidity and structure of 

catalyst particles has been obtained by integrated laser and electron microscopy (iLEM). With this 

approach (Figures e and f) it has been found that the different FCC components are heterogeneously 

distributed throughout the catalyst particles and that the zeolite component is the main Brønsted 

acidic material [2]. 

Figure 1: Confocal fluorescence microscopy images of FCC catalyst particles after reaction with 4-fluorostyrene for (a) 

fresh and (b to d) slightly to severely deactivated particles. Images (e) and (f) display an iLEM experiment of a fresh FCC 

catalyst particle after reaction with 4-fluorostyrene: (e) overlay of fluorescence and TEM image and (f) TEM image only, 

clearly indicating the Brønsted acidic zeolite areas (green fluorescence) and the less acidic matrix materials. 

[1] Chem. Eur. J. DOI: 10.1002/chem.201102949; Nature Chem. 3, 2011, 862. 

[2] Angew. Chem. Int. Ed., 10.1002/anie.201106651. 

31

32 


Chemical Imaging of Cobalt Fischer-Tropsch Catalysts 

Korneel Cats, K.H.Cats@uu.nl, phone: 06 - 22736375 

Sponsor: Shell Global Solutions, since November 2010 


STXM, XAS, Transmission X-ray Microscopy 

Fischer-Tropsch Synthesis (FTS) is an attractive way to convert synthesis gas (a mixture of CO and 

H ) to hydrocarbons. As such, it is an important step in the conversion of biomass, coal or natural 

2 

gas to high-quality fuels and chemicals. Industrially, FTS can be done over a supported iron or 

cobalt catalyst. Of these two, cobalt is the most active catalyst. 

However, deactivation of the cobalt catalyst is an obstacle for industrial application. One of the main 

causes for cobalt catalyst deactivation is sintering, the growth of supported cobalt nanocrystals into 

bigger crystals. This decreases the surface area of the cobalt particles that is available for catalyzing 

the reaction. Unfortunately, the mechanism for the sintering process is currently only poorly 

understood. As a consequence, our possibilities for increasing the stability of the catalyst are limited. 

We aim to improve the understanding of sintering by studying the catalyst with advanced X-ray 

techniques, such as Scanning Transmission X-ray Microscopy (STXM). STXM is a combination 

of X-ray microscopy and X-ray Absorption Spectroscopy (XAS). This will give us detailed 

morphological and chemical information, which will allow us to unravel the mechanism of sintering. 

An important advantage of STXM is that it can be used to study the catalyst under reaction 

conditions (in situ), at elevated temperature and under reactive gas atmospheres. An example of 

in situ STXM is shown in Figure 1. It shows a cobalt catalyst during pretreatment under a H2 atmosphere. The change in color from red to green indicates a change in cobalt oxidation state. 

Figure 1: Chemical maps of a cobalt FTS catalyst during pretreatment. Pixels containing Co 3 O 4 are red, pixels with CoO 

are green and pixels with Co are blue. The left image is at room temperature, the middle image is after 40 min at 350° C 

under H . The left image is after 120 min at 450° C under H . 

2 2


Selective Oligomerization and Polymerization of Ethylene with Cr-based 

Catalysts 

Dimitrije Cicmil, D.Cicmil@uu.nl, phone: 06 - 22736375 

Sponsor: Total Petrochemicals, since June 2011 


Diffuse reflectance UV-Vis-NIR spectroscopy, DRIFTS, Raman spectroscopy 

Ethylene polymerization on the silica-supported chromium catalyst was accidentally discovered 

at Phillips Petrochemicals Company more than half a century ago. Since then it has attracted a 

lot of industrial and scientific attention resulting in modifications of the catalyst material and 

polymerization processes based on the desired polymer properties. 

Polyethylene (PE) is the most produced amongst synthetic polymers. The worldwide production 

capacity is estimated around 80 million tons per year and it is predicted to grow due to excellent 

chemical resistance, high impact strength and stiffness even at low temperature compared to other 

plastic materials. [1] Despite the extensive research in this field, to fully understand the operation of 

the catalyst there are still many questions such as the exact state and structure of the active center, 

the mechanism of initiation and polymerization, and the polymerization kinetics. 

The goal of this project is to utilize various spectroscopic techniques in order to elucidate ethylene 

polymerization/oligomerization on the silica-supported chromium catalyst. [2] 

Figure 1: PE chain growth (upper path) and PE chain termination (lower path) [2]. 

[1] Chem. Rev. 105, 2005, 115. 

[2] Adv. Catal. 53, 2010, 123; Chem. Rev. 96, 1996, 3327. 

33

34 


Integrated Approach to a Combined Diesel Particulate Filter and Selective 

Catalytic Reduction Emission Control System in Heavy Duty Diesel Vehicles 

Upakul Deka, u.deka@uu.nl, Phone: 06 - 22736364 

Sponsor: M2i, since October 2008 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen and dr. Andrew M. Beale 

UV-Vis, IR, MS, XAFS 

The aim of this project is to obtain a fundamental understanding into NH -SCR-based systems 

3 

commonly used for emission abatement in heavy-duty diesel vehicles. Recent work has focused 

on using synchrotron light sources to perform in situ experiments under NH -SCR reaction 

3 

conditions. The pre-determined positions of copper cations within zeolites make it possible to 

combine both long and short range probing techniques to yield information on the structure and 

co-ordination of the active sites. Figure 1 shows the local environment of the active sites in Cu- 

CHA (at different temperatures) using combined X-ray Diffraction and X-ray Absorption Fine 

Structure data collected under relevant gas conditions. This further helps to elucidate the structureperformance 

relationship of the catalysts. 

A second aspect to the work involves synthesis of copper exchanged zeolites using different 

preparation techniques. The catalysts are pre-characterized using conventional laboratory techniques 

such as UV-Vis spectroscopy and X-ray diffraction. The materials are further studied for their 

catalytic activity using an in-house built catalytic rig under plug-flow conditions whilst following 

the output gasses online using infra-red spectroscopy and mass spectrometry. Hence activity/ 

selectivity profiles of catalysts in question are obtained. 

Figure 1: Local structure of copper (light blue) in zeolite CHA under realistic SCR reaction conditions at (a) < 250 °C 

(concurrent with low activity) and (b) > 250 °C (concurrent with > 90% activity).


New stable supported Co catalysts for the Fischer-Tropsch reaction 

Thomas O. Eschemann, T.O.Eschemann@uu.nl, phone: 06 - 22736372 

Sponsor: Shell Global Solutions, since October 2010 

Supervisors: Prof. dr. ir. Krijn P. de Jong and dr. Johannes H. Bitter 

Catalytic testing, TPR, (S)TEM 

The Fischer-Tropsch (FT) reaction, the catalytic conversion of syngas into higher hydrocarbons, 

has been an intense area of research against the background of depleting crude oil resources. [1] 

While in previous research the focus has mainly been on initial activities and selectivities, it is the 

goal of this project to abate deactivation in Fischer-Tropsch catalysts under industrially relevant 

conditions. Deactivation is caused by various factors [3], but in this project most attention will be 

paid on the sintering of the cobalt nanoparticles and how to reduce or slow down this process. One 

method to achieve this goal is to increase the interparticle spacing by achieving a good distribution 

of the active metal species over the support surface, since it can be assumed that the distance between 

the metal particles will influence the sintering properties of the catalyst. 

It is studied how different catalyst preparation methods lead to supported Co catalysts with different 

properties and catalytic behavior. For example, supported cobalt catalysts prepared by incipient 

wetness impregnation (IWI) were calcined in a fluidized bed under different gas flows. Figure 1 

illustrates how the metal clustering can be reduced by changing the gas atmosphere under which 

the catalyst is calcined. In the future, the impact of the catalyst preparation methods on the catalytic 

performance will be studied in detail. Special focus will be paid on the longterm stability of the 

catalysts, using high pressure catalytic testing to mimic industrially relevant conditions. 

20 mm 

Figure 1: Representative TEM pictures of Co catalysts prepared by IWI and calcined under different gases: The dark areas 

on the left side locally indicate very high cobalt loadings, light areas are virtually unloaded. This is in contrast to the 

homogeneous appearance of the catalyst on the right, which indicates a much better distribution of Co on this scale. 

[1] Studies in Surface Science and Catalysis 152, 2004, 533. 

[2] Journal of the American Chem. Society 128, 2006, 3956; Journal of the American Chem. Society 132, 2009, 7197; Journal of 

Catalysis 270, 2010, 146. 

[3] Catalysis Today 154, 2010, 271; Catalysis Today 154, 2010, 162. 

5 mm 

35

36 


Understanding the Synthesis Mechanism and Assembly of Zeolite Materials 

by Raman Spectroscopic Imaging 

Dr. Fengtao Fan, F.Fengtao@uu.nl, phone: 030 - 253 32 63 

Sponsor: PSA Programme Project 08-PSA-M-01, since Dec. 2010 


Raman spectroscopy, AFM, Chemical imaging 

Zeolites are the most well known catalytic materials and usually synthesized from aqueous precursor 

gels under hydrothermal conditions at elevated temperatures. Since the structures of these zeolites 

are critical to their function, investigative work aimed at gaining an understanding of the synthesis 

process has been underway since the 1960s. Up to now, numerous studies have addressed the 

preparation of zeolites and several assembly mechanisms regarding the nucleation and crystal growth 

have been proposed, including the growth from soluble and prefabricated units, autocatalytic 

nucleation, and solid-liquid interfacial nucleation. A basic understanding of the crystallization 

process at a molecular level coupled with this enormous body of existing empirical knowledge 

will provide opportunities for synthesis of new zeolites. 

Raman spectroscopic imaging combined with AFM is becoming probably a most important 

technical development, enabling the studying of structural features of active site in a specific region 

of particles at molecular, nanometer or micrometer scale. We are trying to use Raman spectroscopic 

imaging combined with AFM to study the location of the nucleation site of zeolite, as well as the 

evolution of the zeolite assembly mechanism from precursor to final crystals. 

Figure 1: Raman spectroscopic imaging of AM-6 crystals (in blue color) synthesized with ETS-10 seeds crystals (in pink color).

Preparation of easy regenerable sorbents CO 2 capture 

Dr. Anne Mette Frey, a.m.frey@uu.nl, phone: 06 - 22736090 

Sponsor: CATO2, since January 2012 


CO 2 -TPD, Chemisorption, XRD, TEM 


The ever increasing use of fossil energy in the world brings about the emission of large amounts 

of carbon dioxide into the atmosphere. Carbon Capture and Storage is one of the options to 

mitigate CO emissions. [1] CO capture can be divided in two classes. One method is pre- 

2 2 

combustion capture which involves CO trapped at high temperatures (523- 773 K) accompanied 

2 

by the production of hydrogen, for example via the water-gas shift reaction (CO + H O ↔ CO 2 2 

+ H ). The other method is removal of CO from flue gas streams, e.g. from power plants, at low 

2 2 

temperatures (373- 423 K) which is referred to as post-combustion capture. For the latter, amine 

based scrubbers are currently the commercial option. The use of amines, however, requires the use 

of special reactor materials due to their corrosive nature. [2] Other drawbacks of amines are their 

limited stability during operation, toxicity and need of a solvent (water) to prevent foaming and 

to keep the viscosity low. [3] The use of water as solvent makes the regeneration (desorption of 

CO ) energy intensive, since a considerable amount of energy is used for evaporating the water 

2 

to release the entrapped CO . In this study we want to develop novel regenerable sorbents for the 

2 

CO capture being attractive alternatives to the amine based materials. 

2 

Figure 1: Schematic picture of possible CO 2 capture and storage systems, adapted from Courtesy of CO 2 CRC. 

[1] IPCC, Climate Change 2007: The Physical Science Basis, Cambrigde Univ. Press, Cambridge, 2007. 

[2] Fuel Processing Technology 86, 2005, 1503. 

[3] Industrial & Engineering Chemistry Research 39, 2000, 4346. 

37

38 


Reversibility of H 2 sorption in nanoconfined NaAlH 4 /carbon 

Jinbao Gao, J.Gao@uu.nl, phone: 06 - 22736364 

Sponsor: ACTS, since September 2008 


XRD, TPD/TPR, N 2 -physisorption, SEM 

Hydrogen is a promising energy carrier for both stationary and mobile applications in the future. 

One of challenges that need to resolve is how to realize compact, safe storage of hydrogen. Complex 

metal hydrides are attractive candidates for on board hydrogen storage. However, most of these 

multi-component systems exhibit slow kinetics for H release and especially uptake. Nanosizing 

2 

and confining metal hydrides in a porous material improve H sorption kinetics and reversibility, 

2 

[1] but still no full reversibility has been achieved. 

Nanoconfined NaAlH shows improved reversibility without a metal-based catalyst. However, only 

4 

partial reversibility of desorption was observed (Figure 1). In current study, we discuss the factors that 

limit the reversibility of H sorption by taking nanoconfined NaAlH /C system as an example. For 

2 4 

bulk NaAlH , high pressures and extended charging times are needed to achieve partial reversibility, 

4 

which has commonly be ascribed to the hypothesis that H absorption is limited by solid state 

2 

diffusion of decomposition products, especially Al. [2] Although in nanoconfined NaAlH /C system, 

4 

large Al grains were also formed after full desorption, it is found that the solid Al has a remarkable 

mobility and can be reconverted into nanoconfined NaAlH under mild conditions. Further study 

4 

showed that the major capacity loss occurred after the first dehydrogenation. This is attributed to the 

amount of active Na(H) presented in the dehydrogenated sample that is insufficient to complete the 

reactions with Al and H upon the subsequent rehydrogenation. The loss of active Na(H) species is 

2 

most likely caused by side reactions with impurities, especially O-containing groups on the surface of 

the carbon support. With one-time addition of Na, full reversibility and stable H cycling capacity of 

2 

nanoconfined NaAlH /C can be obtained under relatively mild conditions in absence of any catalyst 

4 

(Figure 1). Our finding is also applicable to other nanoconfined complex metal hydrides systems, as 

illustrated by the increased reversibility of nanoconfind LiBH /C with addition of extra Li(H). This 

4 

is the first time that shows the loss of active alkali metal species caused by reactions with impurities 

in carbon matrixes can play important role on obtaining partial reversibility in nanoconfined systems. 

[1] ChemSusChem 3, 2010, 1332. 

[2] J. Alloys Compd. 302, 2000, 36. 

[3] J. Phys. Chem. C 114, 2010, 10. 

Figure 1: 1 st and 2 nd H 2 release of nanocomposites 

with Al / Na molar ratios of 1.0 and 0.8.


Non-invasive Chemical Mapping of Catalyst Bodies by Diagonal Offset Raman 

Spectroscopy 

Dr. Emma K. Gibson, E.K.Gibson@uu.nl, phone: 06 - 22736090 

Sponsor: Aspect, since June 2011 


Raman Spectroscopy, EDX, Catalyst Bodies, Chemical Imaging 

Many industrial heterogeneous catalysts are prepared in the form of metals or metal oxides dispersed 

on porous high surface area support materials. For fixed bed reactors mm-sized extrudates are 

used to limit pressure drop. The distribution of the active phase in the extrudate can be tailored 

for specific catalytic processes. For example the active phase can be homogeneously distributed, 

concentrated on the external surface, at the centre or in a region between the centre and the edge. 

[1] To determine the active phase distribution in catalyst bodies many techniques can be employed 

such as Raman and UV-Vis micro-spectroscopy, magnetic resonance imaging, tomographic energy 

dispersive diffraction imaging and absorption X-ray tomography. Yet none are both noninvasive 

and provide species specific chemical information. 

Diagonal Offset Raman Spectroscopy (DORS), recently developed in our group, provides noninvasive 

chemical specific analysis of the interior of catalyst bodies. [2] DORS is a modification of 

Spatially Offset Raman Spectroscopy (SORS) [3] optimized for the study of catalyst bodies. During 

DORS a series of Raman spectra are collected where the distance (offset) between the point of 

illumination by the laser and the point of detection is varied. The catalyst body can be rotated 

through 360° and varied in height, in this way species specific information can be gathered from 

the surface, subsurface or bulk regions at any point of the catalyst body in a noninvasive manner. 

Importantly, this technique avoids the risks associated with UV-Vis or Raman micro-spectroscopy, 

where the catalyst body is bisected, exposing the interior to potential environmental changes. 

Currently, it is being tested against idealized catalyst bodies and industrially prepared samples, 

comparing results obtained with traditional backscatter Raman measurements and Energy dispersive 

X-ray spectroscopy. 

Figure 1: The DORS set up [2] showing the movement of the catalyst body for alignment of the laser probe and collection 

head to measure the surface (red), subsurface (blue) and bulk (green) spectra of a NiO/CaAl O catalyst body impregnated 

2 4 

with 1 M NH NO solution. 

4 3 

[1] Ind. Eng. Chem. Prod. Res. Dev. 20, 1981, 439. 

[2] Angew. Chem. Int. Ed., 2011, DOI: 10.1002/anie.201107175. 

[3] Appl. Spectrosc. 60, 2006, 758. 

39

40 


CO Hydrogenation to Light Alkenes over Fe-based Catalysts: An in-situ 

µ-Spectroscopic View on Catalyst Synthesis, Activation and Reaction Processes 

Dr. Inés D. González, I.D.GonzalezJimenez@uu.nl, phone: 06 - 22736379 

Sponsor: Dow Chemical Company, since January 2010 


TXM, EXAFS, XRD, XPS 

Increasing oil and gas prices are driving the industry towards the development of new processes based 

on cost advantaged feedstock like natural gas, coal and biomass. Within the alternative feedstock, 

syngas-based chemistry is an important option. A direct route from syngas to olefins from CO 

hydrogenation (FTO process) will give a competitive solution compared to existing technology 

like MTO since less process steps are applied. 

Recent developments of in situ spectroscopy techniques have proven the importance of in situ 

characterization of heterogeneous catalysts under working conditions as the best way to gain more 

insight into the structure-performance relationships. In the case of FTO, the active sites are situated 

on metal nanoparticles, which consist commonly of Fe, where the addition of promoters can improve 

the catalytic activity and affect to the selectivity towards light olefins. By characterizing the catalyst 

under realistic working conditions (350° C and 10 bar) by TXM we can study the reduction degree 

and its distribution within a micrometer sized particle by monitoring the Fe K-edge with time on 

stream (see Figure 1). 

Therefore, we aim to investigate these systems using different in-situ spectroscopic and microscopic 

techniques to gain fundamental insight in the catalysis functioning. 

Figure 1: 2D chemical composition maps showing the spatial distribution of different iron species over a 21 x 21 micrometer 

particle under helium (a) and after 2 h of reaction (b); green for Fe TiO , red for Fe O and blue for Fe O . (c,d) Fe K-edge 

2 5 2 3 3 4 

bulk XANES spectra of the whole particle and phase composition. Experimental data are noted by (•) and (⎯) indicates 

fitted data, respectively.

Aliphatic olefins from fatty acids 

Rob Gosselink, R.W.Gosselink@uu.nl, phone: 06 - 22736372 

Sponsor: Catchbio, since April 2009 


TPD-MS, XPS, GC, TEM 


Decarboxylation of fatty acids to hydrocarbons is a viable route to arrive at a 2 nd generation biodiesel. 

Pd shows promising activity for the decarboxylation of fatty acids.[1] It is also known that varying 

the support has drastic effects on the activity. However, no fundamental studies were performed 

on the role of the support for this reaction. Therefore we investigated the influence of support 

polarity for this reaction. Carbon nanofibers (CNF) were used as model support for the Pd catalyst 

since these are uniform, mesoporous and pure, making up an ideal support for fundamental studies. 

HNO gas phase oxidation (GPO) was used as a tool to tune the support polarity by introducing 

3 

oxygen groups onto the support.[2] 

Introduction of oxygen groups resulted in a significant increase in the overall activity with a factor 

of ~5. This is tentatively explained by an increased interaction between the carboxylic group of the 

fatty acid and the support. This then favors the number and/or orientation of stearic acid molecules 

in the vicinity of the active Pd site, enhancing the activity. 

Figure 1: Activity of Pd/CNF with low and high support oxygen content over time for the decarboxylation of stearic acid. 

[1] Ind. Eng. Chem. Res. 45, 2006, 5708; Cat. Tod. 106, 2005, 197. 

[2] Gosselink, R.W. et al. Carbon, submitted. 

41

42 


Development of a hydrothermal stable non-noble metal catalyst for 

Aqueous Phase Reforming 

Tomas van Haasterecht, T.vanHaasterecht@uu.nl, phone: 06 - 22736372 

Sponsor: Catchbio, since January 2009 


H 2 -Chemisorption, HPLC/RID, GC/TCD, AAS 

Aqueous phase reforming (APR) of renewable carbohydrates is an attractive process for the 

sustainable and economical production of H . The generated H can be used for efficient power 

2 2 

generation in a PEM fuel cell. Using APR with microreactor technology and an integrated fuel 

cell, we aim for the development of a compact power producing unit for portable applications, this 

part of the project is in collaboration with the TUE. 

In the APR process biomass derived oxygenated hydrocarbons are converted into, preferably H2 and CO , around 500 K using heterogeneous metal catalysts. 

2 

So far the process has been most successful using expensive platinum based catalyst and glycols as 

feedstock. [1] This research focuses on the development of a stable, non noble metal catalyst for the 

efficient and selective production of H from various biomass feeds. The most promising catalyst 

2 

can be integrated in the microreactor system at the TUE to demonstrate the applicability. 

We have investigate the possibility of using Carbon Nanofiber (CNF) supported Co, Ni and Cu 

catalysts with a focus on their hydrothermal stability. These catalysts, and a commercial 5%Pt/Al O 2 3 

catalyst, were tested in a batch reactor for the APR of a 1% Ethylene Glycol (EG) solution. The 

resulting conversion profiles are shown in Fig. 1. The highest conversion was achieved with the 

Ni/CNF catalyst while the Cu/CNF is almost inactive. The initial activity in terms of TOFi,EG 

is highest for the Co/CNF catalyst, however after an initial period of high activity the Co/CNF 

catalyst appears to deactivate. 

Indeed XRD analysis of the spent catalysts shows that Co/CNF is subject to sintering and oxidation. 

The Ni, Cu and Pt catalysts remain metallic, but sintering also occurs for the Ni/CNF catalyst. 

Furthermore, the amount of leached metal, detected in the liquid phase after the reaction, was 

significantly higher for the Co/CNF catalyst compared to other catalysts. Based on these result the 

Ni/CNF is the most promising alternative to platinum based catalyst in terms of activity and stability. 

Figure 1: EG conversion as function of time. 

[1] Appl. Catal. B. 56, 2005, 171.


Spatial Studies of the SERS Effect for Heterogeneous Catalysis Investigations 

Clare E. Harvey, C.E.Harvey@uu.nl, phone: 06 - 22736375 

Sponsor: NRSC-C, since September 2008 


Raman Spectroscopy, Atomic Force Microscopy (AFM), AFM-Raman, Surface Enhanced Raman Scattering 

(SERS) 

Supported metal nanoparticles are important heterogeneous catalysts in many industrial processes. 

A thorough understanding of which specific surfaces, have the highest catalytic activity is required 

in order to tune the shape and size of nanoparticles to reach the maximum catalytic activity. [1] 

Raman spectroscopy has proven to be a powerful and versatile tool for the study of chemical reactions, 

but lacks sensitivity under normal measurement circumstances. The use of surface enhancement 

makes Raman spectroscopy a much more sensitive and versatile tool for the study of chemical 

reactions. Surface Enhanced Raman Scattering (SERS) occurs principally on roughened noble metal 

surfaces or noble metal NPs, and allows chemical imaging of adsorbate-surface interactions with 

high sensitivity. This makes it uniquely suited for investigations of reactions at a catalytic surface. 

The integration of Atomic Force Microscopy (AFM) with Raman spectroscopy forms a powerful 

new tool for nano-scale chemical imaging of catalytic solids, allowing nano-scale morphological 

features to be correlated directly to chemical information. [2] 

My studies are currently focusing on using integrated AFM-Raman measurements to study the 

Surface Enhanced Raman Scattering (SERS) phenomena of supported nanoparticles under in-situ 

conditions, and investigating methods of increasing the applicability of SERS for heterogeneous 

catalysis investigations. 

Figure 1: Overlapping AFM and Raman images of agglomerations of Ag NCs and Rhodamine-6G (Rh6G) on an Al 2 O 3 wafer; (A) 

AFM height image of surface; (B) AFM magnification of an area over which Raman intensity was followed (scale bar = 200 

nm); (C) Raman spectra followed over time from (B); (D) Raman intensity map of the Rh6G band at 1512 cm-1 . 

[1] Chem. Rev. 95, 1995, 511. 

[2] Chem. Commun., DOI: 10.1039/c2cc15939b; Angew. Chem. Int. Ed. 48, 2009, 4910. 

43

44 


Pd/TOMPP-Catalyzed Telomerization of 1,3-Butadiene: From Biomass-Based 

Substrates to New Mechanistic Insights 

Peter J.C. Hausoul, P.J.C. Hausoul@uu.nl, phone: 06 - 22736364 

Sponsor: ACTS-ASPECT, since February 2008 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen, Prof. dr. Robertus J.M. Klein Gebbink and 

dr. Pieter C.A. Bruijnincx 

Organometallic synthesis, High performance liquid chromatography, NMR spectroscopy, X-ray crystallography 

Biomass-based resources, such as glycerol, cellulose and lignin, are a potential feedstock for bulk and 

fine chemical synthesis. A promising technology for the conversion of these polyhydric compounds 

is the Pd-catalyzed telomerization of 1,3-butadiene (Scheme 1), which converts alcohols into the 

corresponding C8-ethers, which after hydrogenation find application as surfactants and cosmetics 

components. 

Scheme 1: Pd/TOMPP-catalyzed telomerization of 1,3-butadiene with alcohols. 

Previously, we showed that Pd/TOMPP (tris(2-methoxyphenyl)phosphine) is a highly active and 

selective telomerization catalyst for the conversion of various biomass-derived substrates [1]. In 

case of carbohydrate substrates with hemi-acetal groups, deactivation occurred and it was found 

that TOMPP is converted towards 2,7-octadienyl phosphonium species (G) during the reaction.[2] 

Stoichiometric reactions show that this pathway is reversible in the presence of Pd(0) and a catalytic 

amount of ligand and results in the key catalytic intermediate [Pd(1-3,7,8-η-octa-2(E),7-dien-1yl)(PR 

)]BF (C) (Scheme 2). The catalytic performance could be improved by using Pd(dba) as 

3 4 2 

precatalyst instead of Pd(acac) . These insights were also used to synthesize complexes of type C with 

2 

a range of different phosphine ligands and allowed more detailed studies regarding the reactivity of 

these species to be conducted.[3] 

Scheme 2: Reversibility of phosphonium formation. 

[1] ChemSusChem 1, 2008, 193; Chem. Eur. J. 14, 2008, 8995; Green Chem. 11, 2009, 1155; ChemSusChem 2, 2009, 855. 

[2] ChemCatChem 3, 2011, 845. 

[3] Angew. Chem. Int. Ed. 49, 2010, 7972.


Thin Film Model Catalysts for AFM-Raman Studies on Catalyst Deactivation 

Mechanisms in the Liquid Phase 

Dr. Jan Philipp Hofmann, J.P.Hofmann@uu.nl, phone: 06 - 22736392 

Sponsor: www.DFG.de (HO4579-1); NRSC catalysis, since March 2011 


AFM-Raman 

Catalyst deactivation in the conversion of plant biomass – a renewable alternative feedstock for 

production of fuels and chemicals – is a major hurdle for the realization of new catalytic processes 

in terms of a so-called bio-refinery concept. In contrast to crude oil related processes, conversions 

of biomass derived oxygenates takes place in polar liquid phase environments, which sets totally 

new requirements for catalyst design. 

To get deeper insight into catalyst stability and deactivation mechanisms, a combination of scanning 

probe microscopy methods (SPM) and Raman spectroscopy will be applied on flat model catalysts [1]. 

The model catalysts consist of flat substrate (Si or glass) coated with a metal oxide support layer, 

prepared by a sol-gel approach; the active phase (Pt group metals) is deposited in the form of 

nanoparticles or nanofibers, mimicking industrially applied supported noble metal catalysts. 

Combining SPM and Raman spectroscopy will yield both topological as well as chemical 

information of the thin film model catalyst in a laterally resolved manner. In situ measurements in 

liquid phase environments are possible and allow for a detailed analysis, how reaction parameters, 

such as temperature, pH value, and the presence of organic molecules, contribute to the catalyst 

deactivation mechanisms, depicted in Fig. 1. 

Figure 1: Catalyst deactivation processes in liquid phase conversion of polar organic molecules derived from biomass. 

The first results indicate the applicability of the approach. Various metal oxide thin films (TiO , 2 

Al O , SiO …) could be prepared with controlled porosity. Catalytically active metal structures have 

2 3 2 

been synthesized via standard nanoparticle routes and electrospinning (fibers). 

[1] Chem. Commun., (in press), 2012, DOI:10.1039/C2CC15939B. 

45

46 


Building the Renewable Lignin Platform: New Heterogeneous Catalyst 

Technology for the Production of Chemicals and Fuels from Biomass 

Robin Jastrzebski, R.Jastrzebski@uu.nl, phone: 06 - 22736361 



Catalytic testing, NMR, GC-MS, UV-Vis 

Lignin is a major (18-40 wt%) component of wood and would thus form an important process 

stream in future biorefineries to provide society with a sustainable source of fuels and chemicals. 

The structure of lignin is best described as a three-dimensional cross-linked polymer of oxygenated 

phenylpropane units (Figure 1). Although this is a potentially valuable source of aromatics and other 

functionalised hydrocarbons, the complex structure also poses problems in depolymerisation and 

further processing of the product mixture. [1] 

My project aims to develop new catalytic systems for the depolymerisation of lignin and 

converting the products into value-added bulk chemicals and fuel components. Novel methods 

for depolymerisation may be based on recently reported homogeneous nickel systems. [2] Emphasis 

will also be on convergent conversion of a large number of depolymerisation products into a limited 

number of platform molecules, for example through the use of biologically inspired catalysis. [3] 

Figure 1: Schematic representation of lignin structure with important linkages highlighted. 

[1] Chem. Rev. 110, 2010, 3552. 

[2] Science 322, 2011, 439. 

[3] Nature 455, 2008, 333.


Fundamental Studies on the Catalytic Conversion of Lignin and Related Model 

Compounds 

Annelie Jongerius, A.L.Jongerius@uu.nl, phone: 06 - 22736361 

Sponsor: CatchBio since April 2009 


NMR spectroscopy, GC-MS, GPC, catalytic testing 

Lignin is a three-dimensional cross-linked biopolymer consisting of a phenyl-propane repeating unit, 

optionally substituted with methoxy and hydroxyl goups that forms an integral part of the secondary 

cell walls of plants. It is the second most abundant fraction of biomass and comprises about 18-40 

wt% of the dry mass of wood. Conversion processes for the cellulose and hemi-cellulose fraction 

of biomass results in significant process streams of lignin, which until this moment are primarily 

used for the generation of energy. 

Currently, the most important starting materials for the production of bulk chemicals are olefins 

and aromatics and the major fraction of these intermediate building blocks are produced by steam 

cracking of naphtha. It would be attractive if the same chemical intermediates could be produced 

from the unused biomass components like lignin. 

This project aims to develop fundamental knowledge, which would allow directly converting this 

unused wood fraction into aromatic intermediates for bulk chemicals production. For this purpose, 

both catalytic and mechanistic studies will be done with lignin as well as various di- and monophenolic 

model compounds. Based on this knowledge we wish to explore the development of a 

two-stage process for the conversion of lignin into aromatic compounds in high yields. 

[1] J. Catal., 285, 2012, 315. 

[2] Chem. Rev. 110, 2010, 3552. 

47

48 


Theoretical investigation on the X-ray absorption spectra of transition metal 

systems 

Reshmi Kurian, R.Kurian@uu.nl, phone: 06 - 22736392 

Sponsor: NWO VICI, since April 2011 

Supervisor: Prof. dr. Frank M. F. de Groot 

XAS, Charge transfer multiplet calculations, Ab-initio calculations, DFT 

X-ray absorption spectroscopy (XAS) is a powerful tool for fundamental studies on isolated molecules 

as well as for the characterization of solid materials. XAS has the advantage of site specificity, allowing 

the selection of different core level edges of interest, and detailed information on the electronic 

and structural environment of a particular element in a given compound can be obtained.[1] The 

advances in the experimental field have enabled the measurement of the transition metal absorption 

edges with great accuracy. The metal L edge structures observed in the first row transition metal 

compounds involve 2p3d electric-dipole transitions and the transition intensity directly reflects the 

amount of 3d metal character in the low-lying empty states. Similarly, the K edge derives from the 

allowed transitions from a metal 1s orbital to the 3d states. The interpretation of the experimental 

absorption spectrum is crucial but it is not straightforward, therefore it is important to do the 

computational spectral calculations within various quantum chemical and semi empirical codes 

and compare it with the experiment. 

The main aim of our work is to study the process of X-ray absorption on transition metal systems, 

both molecular complexes and bulk oxides in relation to electronic structure calculations of matter. 

The L edge XAS, where the multiplet effects dominate the spectral shape, the crystal field and 

2,3 

charge transfer multiplet program will be used for the investigation,[2] whereas the K edge spectral 

calculations is carried out within various quantum chemical codes. 

A number of special interests are, [1] The comparison between the Fluorescence Yield (FY) and 

XAS calculations of the transition metal atoms. This study is credential as the FY measurements of 

core-level absorption edge spectra is generally used as a good measure of the X-ray absorption cross 

section. [2] The electronic structure of cobalt oxides are studied from the analysis based on the K 

edges of XAS. These investigations are highly relevant and will give an insight into the electronic 

structural variations as well as the absorption and decay mechanisms of the transition metal systems. 

[1] Core level Spectroscopy of Solids, Taylor & Francis, New York, 2008. 

[2] Micron 41, 2010, 687.


Integrated Investigation and Approach to a Combined DFP and SCR 

Emission Control System: Fundamental Understanding on How to Combine 

SCR-DPF for Emissions Abatement 

Dr. Ines Lezcano-Gonzalez, I.LezcanoGonzalez@uu.nl, phone: 06 - 22736379 

Sponsor: M2i, since May 2011 


XRD, XAS, NMR, UV-Vis, IR, MS 

The overall objective of this project is to obtain a fundamental understanding into the integration 

of selective catalytic reduction (SCR) and diesel particulate filtration (DPF) technologies, in order 

to provide a pathway to the next generation of emission control systems. This will be achieved by 

studying each system in detail, in order to determine the sites responsible for catalytic activity as 

well as the effect of both thermal and chemical deactivation on the catalytic performance. 

Deactivation of diesel exhaust gas catalyst materials is an important problem that has to be solved 

in order to control the activity and selectivity of the catalysts and guarantee their stability under 

reaction conditions. The most relevant deactivation phenomenon during normal vehicle operation 

occurs as a result of either chemical or thermal mechanisms. Exposure to high operation temperatures 

enhances the reduction of the catalyst surface area and sintering of the metals responsible for 

catalytic activity, whereas the presence of some pollutants, such as sulphur or phosphorus, results 

in contamination of the washcoat and the active sites. 

Therefore, a primary goal of this project is to investigate the individual and combined effects 

of various poisons, as well as the combined influence of poisoning and thermal deactivation. 

This will be done using either conventional or advanced characterization techniques, including 

X-ray Diffraction (XRD), Nuclear Magnetic Resonance (NMR), UV-Vis Spectroscopy or X-ray 

Absorption Spectroscopy (XAS). 

49

50 


Nano-reactors for catalysis 

Rafael Lima Oliveira, r.delimaoliveira@uu.nl, phone: 06 - 22736375 

Sponsor: NRSCC, since February 2011 


Mesoporous silica, N2 physisorption, XRD 

Ordered mesoporous materials have large surface areas, uniform pore sizes and tunable periodic 

structures. These properties make these materials attractive in various fields, for example: drug 

delivery, sensors, separation and catalysis. Mesoporous silica is a promising material as support for 

nanoreactors in catalysis because silica is able to form many different pore structures, such as 2D 

and 3D mesostructures. [1] Nanoreactors are small involucres, cavities or partially blocked pores 

where chemical reactions can take place (Figure 1). This physical barrier selects molecules which 

an appropriate size for entering and leaving the reactor. 

Figure 1: Schematic picture of the pore blocking and cavities on mesoporous structure. 

In catalysis, many efforts have been spent to disperse and stabilize metal nanoparticles inside 

mesoporous silica. The synthesis of metal nanoparticles with good dispersion and a high thermal 

stability has been showed difficult. The stabilization of these particles is very important to avoid 

mobility and leaching of metal and as consequence growth of particles and loss on catalyst activity. [2] 

In this research project, we are investigating the synthesis of different mesoporous structures, such 

as: SBA-15 and MCM-41, to obtain plugged hexagonal template silicas with nanoconfined spaces. 

[3] In these spaces, we deposit nanoparticles of palladium for application in carbon-carbon coupling 

reaction, for example the Heck reaction. These particles present in nanoconfined spaces are expected 

to be more resistant for leaching and mobility avoiding the formation of large particles and loss 

of catalyst activity after performance. The characterization of these materials will be done using 

techniques, such as electron microscopy, N physisorption, H chemisorption, X-ray diffraction 

2 2 

and others. 

[1] Chem. Rev. 107, 2007, 2821. 

[2] Chem. Eur. J. 14, 2008, 7478. 

[3] J. Phys. Chem. B 106, 2002, 5873.


Fundamental Studies on the Catalytic Hydrogenation of Levulinic Acid 

Wenhao Luo, W. Luo@uu.nl, phone: 06 - 22736375 

Sponsor: Catchbio, since September 2009 


GC-MS, ATR-IR, TPD-NH 3 , AAS 

Levulinic acid (LA) has been identified as a promising renewable platform molecule, which can be 

converted to various less-oxygenated derivatives by controlled catalytic hydrogenation/ deoxygenation. 

This way, valuable renewable chemicals, such as γ-valerolactone (GVL), methyltetrahydrofuran 

(MTHF), pentanoic acid (PA) and its esters (PE) can be obtained. The products can be used as 

renewable fuels, additives, solvents and chemical building blocks (Figure 1). 

Figure 1: Levulinic acid hydrogenation platform [1]. 

The project aims for the selective hydrogenation of LA with heterogeneous catalysts. A combined 

catalytic and spectroscopic study will be performed, with the aim of identifying catalyst-product 

relations. For example, in situ attenuated total reflection (ATR) infrared (IR) spectroscopy (Figure 

2), allowing the on-line detection of intermediates and products during catalytic conversion, will 

be applied to unravel the factors determining the selectivity of this conversion process. 

Figure 2: In situ attenuated total reflection infrared (ATR-IR) setup. 

[1] Science 327, 2010, 1110; Angew. Chem. Int. Ed. 49, 2010, 4479. 

51

52 


Designing Bifunctional Nano-Alloy Catalysts for Bio-Renewable Fedstock 

Valorisation 

Dr. Sankar Meenakshisundaram, M.Sankar@uu.nl, phone: 030 - 253 32 63 

Sponsor: ERC (Marie Curie Intra European Fellowship), since May 2011 


Bimetallic nanoalloys, in-situ FTIR, EXAFS, Catalytic Testing 

The principal goal of this project is to develop efficient and selective bi-functional catalyst systems 

having both acid/base catalysed and an oxidation functionalities for the valorisation of biomass 

to produce bulk/speciality chemicals effectively in an environmentally benign route. Oxidative 

valorisation of the lignin and cellulosic constituents of biomass for the production of value added 

products by bi-functional heterogeneous catalysts using environmentally benign oxidants like O or 2 

H O in a green solvent medium is the key aspect. [1] The proposed bifunctional nano-alloy catalyst 

2 2 

will also be tested for the oxidation of bio-renewable feedstock materials (platform molecules) 

and model compounds using green oxidants like O or H O in an ionic liquid medium replacing 

2 2 2 

stoichiometric oxidants like permanganates or chromates. 

We intend to use the catalyzed oxidative dehydrogenation of bio-renewable benzylic alcohols 

(e.g., veratryl alcohol, vanillyl alcohol and cinnamyl alcohol) as a substrate activating strategy for 

the synthesis of amines, benzimidazoles, and as a general strategy for the N-alkylation of amines 

in a single pot. [2] 

In situ spectroscopic techniques, like ATR-IR, UV-Vis, Raman, along with X-ray absorption 

methods (e.g. XAFS, including XANES and EXAFS as well as related microscopy methods, such as 

STXM), coupled with isotopic labelling studies would be employed to understand the interaction 

between substrates and catalysts, especially to characterize the adsorbed species and the compositional 

effects of the nano-alloys made and during catalytic reaction. It is proposed to study the feasibility of 

performing some of the above mentioned reactions in a continuous fashion using different reactors 

like fixed bed reactor (FBR), micropacked bed reactors (MPBR). 

[1] Chem. Rev. 110, 2010, 3552. 

[2] Chem. Rev. 110, 2010, 1611.


Electronic structure determination of cobalt- and iron-phthalocyanine in a 

magnetic field and in-situ Oxygen adsorption using X-ray spectroscopies 

Piter S. Miedema, P.S.Miedema@uu.nl, phone: 06 - 22736361 

Sponsor: NWO-CW/VICI since May 2008 

Supervisor: Prof. dr. Frank M.F. de Groot 

X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Charge transfer multiplet 

calculations, Density functional theory (DFT) 

Cobalt-phthalocyanine (CoPc) and iron-phthalocyanine (FePc) mono- and multi-layers were 

studied on a gold (Au(111) surface in a magnetic field of B=5T with Metal L -edge X-ray 

2,3 

absorption spectroscopy depending on the polarization of the X-rays (X-ray magnetic circular 

dichroism, XMCD). [1] XMCD gives information about the magnetic properties of systems. [2] 

By tuning the empirical parameters of the multiplet program (the crystal field values 10Dq, Ds and 

Dt) one can obtain calculated L -edge XAS spectra and XMCD signals which are similar to the 

2,3 

experimental spectra and at the same time information is received about the electronic (spin) state 

of the metal. In the case of CoPc it was found that the monolayers on gold become non-magnetic 

due to a free gold electron that interferes with the Co 3d holes. For FePc, the monolayer on gold 

z2 

is magnetic, although it loses some spin related to multilayers and the bulk powder. [1] We also 

use in-situ X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) to 

study the electronic properties of FePc and CoPc catalysts at the point that oxygen is adsorbed. 

The experimental data are compared with XAS calculations, using both charge transfer multiplet 

calculations for the metal L -edge and TD-DFT for the nitrogen K-edges. The combination of 

2,3 

the experimental spectra with detailed calculations shows that the oxygen adsorbs differently on 

CoPc and FePc. For the CoPc the oxygen molecule absorbs with only one bond between one 

oxygen atom and the cobalt metal center. This is the so-called Pauling or end-on binding. For FePc, 

the oxygen molecule absorbs mainly in a configuration parallel to the FePc surface, although the 

end-on binding cannot be ruled out. [3] 

Figure 1: CoPc and FePc bind O 2 in different ways. 

[1] PRB 83, 2011, 220401(R). 

[2] PRB 80, 2009, 184410. 

[3] JPCC, 115, 2011, 25422. 

53

54 


Controlling Cobalt Distribution and Dispersion in Supported Catalysts for 

the Fischer-Tropsch Synthesis 

Peter Munnik, P.Munnik@uu.nl, phone: 06 - 22736385 

Sponsor: NWO-CW/TOP, since March 2010 


Microtomy, TEM, DRIFTS 

While the current world economy is highly reliant on crude oil for the production of fuels and 

chemicals, the natural oil reserves are dropping and will eventually run out. Moreover, there is an 

increased demand in high quality products free of contaminants like nitrogen, sulphur and aromatics. 

For this reason, converting other feedstocks such as coal, natural gas and biomass into hydrocarbons 

and other chemicals is an important field of research. These feedstocks can be converted to syngas, 

H and CO, which can then be used as reactants in the Fischer-Tropsch synthesis. In this process, 

2 

the syngas is converted into clean hydrocarbons ranging from methane to hard waxes through the 

use of a heterogeneous catalyst. 

Highly loaded cobalt catalysts supported on silica or alumina have been found to be highly active 

and selective towards long paraffinic chains for this reaction. However, inhomogeneous cobalt 

distributions are often obtained after catalyst preparation, and as a result sintering of the cobalt 

particles during the Fischer-Tropsch synthesis is a major cause of catalyst deactivation. Our goal is 

to gain full control of the cobalt particle dispersion and distribution by studying synthesis conditions 

such as drying, calcination, cobalt precursor and support-precursor interactions in order to make 

the most stable and active catalysts. 

By creating cross-sections of as-synthesized catalyst particles using ultramicrotomy we study the 

distribution of the cobalt phase throughout particles on both the nano- and microscale using TEM, 

STEM and 3D-TEM. In-situ spectroscopic techniques are used to study the decomposition of 

cobalt precursors treated under different conditions, and catalysts are tested to elucidate the effect 

of different cobalt distributions on the activity, selectivity and stability of the catalysts. 

Figure 1: Different degrees of 10 nm Co 3 O 4 nanoparticle clustering on γ-Al 2 O 3 .

Niobia Supported Cobalt Catalysts for Fischer-Tropsch Synthesis 

Arjan den Otter, J.H.denOtter@uu.nl, phone: 06 - 2273 6375 


Sponsor: Companhia Brasileira de Metalurgia e Mineração - CBMM, since July 2011 


N 2 -physisorption, H 2 -chemisorption, TEM 

The present industry mainly relies on the limited reserves of crude oil for the production of 

transportation fuels and other chemicals. Natural gas reserves are reported to be larger but are, 

due to their remote location, not exploited and associated gas might be flared off. However, using 

steam reforming of methane, natural gas can be converted to synthesis gas, a mixture of CO and 

H . Using the Fischer-Tropsch process, catalyzed by supported Co or Fe catalysts, synthesis gas can 

2 

be converted into liquid hydrocarbons with a low concentration of contaminations like nitrogen, 

sulfur and aromatics. 

Key parameters for the performance of industrial catalysts are selectivity, stability and activity. 

Extensive research has been performed on alumina, silica, carbon and titania supported Fischer- 

Tropsch catalysts, whereas only a limited number of studies on niobia supported catalysts were 

performed. In these studies a very promising selectivity towards hydrocarbons in the diesel range was 

reported [1-3]. However, in these studies only limited catalyst characterization was performed and 

mainly catalysts with low metal loading were addressed. Further investigation of niobia supported 

cobalt catalysts is intriguing since niobia is reported to exhibit a tunable acidity [4], important 

during catalyst preparation, and hydrothermal stability [5], crucial to achieve catalyst stability under 

industrial Fischer-Tropsch conditions. In this project niobia supported cobalt catalysts will be 

synthesized using various routes and will be characterized in detail. The catalyst selectivity, stability 

and activity in the Fischer-Tropsch process will be tested and the catalyst preparation methods will 

be adapted to obtain enhanced catalyst performance. 

[1] R.R. Soares, A. Frydman and M. Schmal, Catal. Today 16 (1993) 361-370. 

[2] R.R.C.M. Silva and M. Schmal, J. Chem. Soc. Faraday Trans. 89 (1993) 3975-3980. 

[3] C.D. de Souza, D.V. Cesar, S.G. Marchetti and M. Schmal, Stud. Surf. Sci. Catal. 167 (2007) 147-152. 

[4] S.H. Chai, H.P. Wang, Y. Liang and B.Q. Xu, Green Chem. 9 (2007) 1130-1136. 

[5] H.N. Pham, Y.J. Pagan-Torres et al., Appl. Catal. A 397 (2011) 153-162. 

55

56 


Design and assembly of nanostructured catalysts for the conversion of syngas 

into alcohols 

Dr. Gonzalo Prieto, g.prietogonzalez@uu.nl, phone: 06 - 22736107 

Sponsor: Department of Energy U.S.A. (DoE), Energy Frontier Research Center (Atomic Level 

Catalyst Design), since February 2010 


Inorganic synthesis, Catalytic testing, TEM, Electron tomography 

Dwindling crude oil reserves prompt the development of effective catalytic processes to produce fuels 

and platform chemicals from alternative carbon sources such as natural gas, coal or lignocellulosic 

biomass. Synthesis gas or syngas (CO+H ), which can be obtained from these oil-alternative sources, 

2 

serves as feedstock for versatile catalytic routes towards fuels and platform chemicals. Supported 

metal catalysts are employed in syngas conversion routes but metal sintering is a prominent cause 

of catalyst deactivation. Rationally designing and assembling novel catalysts with improved stability 

remains as a major challenge. 

This project aims at gaining fundamental insight into the factors governing the stability of metalbased 

supported catalysts in syngas conversion processes, e.g. methanol synthesis. To accomplish this 

goal, our approach combines material synthesis, catalytic testing and advance electron microscopy 

characterization (namely electron tomography [1]). Due to their industrial relevance, the research is 

focused on synthesis procedures such as impregnation-drying using inexpensive metal precursors such 

as nitrates. Different aspects such as support pore size/morphology, metal particle size/composition 

as well as the spatial distribution of the active phases at the nanoscale are currently being studied. 

Figure 1: a) 3D segmentation of 

individual Cu nanoparticles in the 

pores of SBA-15; b) evolution of 

catalytic activity with run-time for 

CuZn/SBA-15 catalysts with markedly 

different spatial distributions of the 

supported Cu nanoparticles and a 

reference Cu/ZnO/Al O catalyst. 

2 3 

As illustrated in Fig.1, CuZn/SBA-15 catalysts can be synthesised with similar overall (bulk) 

properties but vastly d¡ffering in the nanospatial distribution of the catalytic Cu nanoparticles, as 

quantitatively accessed by electron tomography (panel a in Fig. 1). Near-maximum interparticle 

spacings result in up to an order of magnitude enhancement in the catalyst stability under realistic 

methanol synthesis conditions with respect to a more “clustered” Cu distribution or a commerciallyrelevant 

Cu/ZnO/Al O reference catalyst (panel b). These results highlight the tremendous 

2 3 

importance of collective features of the supported nanoparticles (i.e., their nanospatial distribution) 

for catalyst stability under realistic process conditions. 

[1] Chem. Rev. 109, 2009, 1613.


An In-situ Micro-spectroscopic Study of Alcohol-to-Olefin Conversions on 

Individual CHA Zeolite Crystals 

Qingyun Qian, Q.Qian@uu.nl, phone: 06 - 22736375 

Sponsor: NRSC-Catalysis, since October 2009 


Confocal fluorescence microscopy, UV-Vis micro-spectroscopy, IR micro-spectroscopy 

The selective conversions of Alcohol-To-Olefins (ATO) have attracted large interest as these 

processes are considered alternative processes to bypass crude oil as a feedstock for the production 

of refinery products, such as propene. One of the most studied processes is the Methanol-To-Olefins 

(MTO) process as methanol can be produced from syngas, a mixture of CO and H2, which on its 

turn can be obtained from crude oil alternative resources, such as biomass, natural gas or coal. MTO 

reaction is efficiently catalyzed by various protonated zeolites or zeotype materials. Our study is 

focused on SAPO-34, the archetypal MTO catalyst and its all silica variant SSZ-13, which both have 

the CHA-topology with large cavities (0.65 nm × 1.1 nm) connected through small channels (0.42 

nm × 0.37 nm). The acidic centers of SAPO-34 are responsible for the chemical transformation of 

methanol into valuable hydrocarbons, while its pore architecture offers well defined confined spaces, 

showing a high selectivity towards light olefins. However, SAPO-34 experiences rapid deactivation 

by coke deposition, thereby affecting their potential application on an industrial scale. 

Mechanistic investigation of coke formation during alcohol conversions therefore is important as 

it is essential for the study of the activity and selectivity of the zeolites. An indirect route called 

“hydrocarbon pool (HP) hypothesis” of MTO reaction has been well accepted. Understanding the 

generation and activity of HP species thus can help us to gain new insight into ATO processes. 

Our recent work included both studies of MTO and ETO reactions on individual SAPO-34 

and SSZ-13 large crystals using a combination of in-situ micro-spectroscopic techniques. One 

example is to compare the rate of coke formation of different alcohol conversions on SAPO-34 

crystals. Therefore, UV-Vis micro-spectroscopy followed by a deconvolution procedure and confocal 

fluorescence microscopy were applied to investigate differences during coke formation of MTO 

and ETO reactions in both kinetic and mechanistic point of view (Figure 1). 

[1] Micropor. Mesopor. Mater. 29, 1999, 3; Chem. Eur. J. 14, 2008, 11320. 

Figure 1: Rate constant k of the 400 nm Gaussian band (major HP species) 

as a function of temperature during the reaction of methanol, ethanol 

and a mixture of both over SAPO-34 crystals. 

57

58 


Single Molecule Chemical Imaging of Zeolite Crystals at the Nanoscale 

Zoran Ristanović, Z.Ristanovic@uu.nl, phone: 06 - 22736372 

Sponsor: NRSCC, since May 2010 


Single molecule fluorescence microscopy, Confocal fluorescence microscopy, Synchroton based IR microspectroscopy 

In the last years application of numerous in-situ micro-spectroscopy techniques to the family of 

zeolites have resulted in new insights in surface and internal transport barriers for molecular diffusion. 

[1] Unfortunately, diffraction limitations and ensemble averaging prevent researchers from having 

more fundamental insight into single catalytic events. Therefore, optically unlimited spectroscopic 

tools would help understanding the dynamics of guest molecules on the individual active sites, as 

well as the observations of spatiotemporal heterogeneities at the single particle level. 

In this work wide-field fluorescence microscopy has been used as a powerful tool for probing the 

Brønsted acidity of zeolite crystals at the single molecule level. [2] Following this novel approach, 

the Brønsted acid-catalyzed oligomerization of 4-methoxystyrene and 4-fluorostyrene has been 

developed for imaging the distribution of Brønsted acid sites within micron-sized ZSM-5 crystals. 

In this way intrinsic catalytic heterogeneities are easily accessible on the single molecule level. The 

spatial distribution of active sites has been mapped by counting single turnover events with high 

lateral (10-15 nm) and temporal resolution (30 ms per frame). The catalytic activity was also recorded 

as deep as 10 microns inside the zeolite particles, as illustrated in Figure 1. 

Figure 1: Methoxystyrene oligomerization reaction as 

recorded 10 microns below the surface of micron-sized 

zeolite H-ZSM-5 crystals. a) CCD intensity color-coded 

representation of the crystal reactivity during 100 ms 

long frame, b) corresponding single molecule reactivity 

map reconstructed over 5000 frames (1 frame = 100 ms). 

The obtained results have been supported by related data obtained with confocal fluorescence 

microscopy and synchrotron based infrared microscopy, connecting single catalytic events with 

essential chemical information on the nature and the orientation of active species. The ultimate 

sensitivity of the techniques explored, combined with the pronounced photo-stability of the 

detected fluorescent products can be used to describe and quantify the interaction of molecules 

within zeolite frameworks, opening new possibilities in the imaging of active sites and exploring 

host-guest chemistry at the single molecule level. 

[1] Angew. Chem. Int. Ed. 48, 2009, 4910. 

[2] Chem. Soc. Rev. 39, 2010, 4703.


Deactivation of Individual Cracking Catalyst Particles Revealed by a Multi- 

Technique Synchrotron-Based Approach 

Dr. Javier Ruiz-Martínez, J.RuizMartinez@uu.nl, phone: 030 - 251 10 27 

Sponsor: ASPECT, since October 2009 


XAS, Microfocus X-ray fluorescence, XRD tomography 

Fluid catalytic cracking (FCC) is an important catalytic process to convert heavy oil fractions 

into more valuable chemicals, such as gasoline and olefins. [1] During cracking, the activity of the 

catalyst particles decreases due to deactivation. The detrimental effects of metals coming from the 

oil feedstock, especially Ni and V, on FCC catalysts have been widely recognized in the literature. 

[2] These metals deposit on the catalyst and act as poisons, damaging the zeolite structure, decreasing 

the accessibility and favoring dehydrogenation-hydrogenation reactions that subsequently lead to 

an increase in coke formation. 

In this project, we have developed an approach consisting of a combination of μ-XRF, μ-XANES 

and μ-XRD for the characterization of metal poisons and their detrimental effect on individual 

FCC catalyst particles. μ-XRF and μ-XANES spectra would provide information on the distribution 

and chemistry of metal poisons, whereas μ-XRD data would reveal the distribution of the zeolitic 

material, the active phase, as well as its deactivation, i.e. dealumination, under real catalytic conditions. 

Figure 1: Nickel and vanadium μ-XRF maps of the deactivated FCC catalyst particle. Orange lines illustrate the position 

where the fluorescence intensity profiles were taken. (c) One-dimensional fluorescence intensity profiles as a function of 

the position inside the FCC catalyst particle, derived from the 2D-images. Nickel is represented in green and vanadium in 

blue. μ-XRD tomography reconstruction of the zeolitic phase for a (d) fresh and (e) deactivated FCC catalyst particle. (f) 

XRD patterns of the fresh (black) and deactivated (blue) samples. 

[1] Handbook of Heterogeneous Catalysis, Wiley, 2008. 

[2] J. Catal. 168, 1997, 1; J. Catal. 2007, 2002, 237. 

59

60 


In-situ STXM analysis of Al 2 O 3 supported CoMoS catalyst for the HDS process 

Mustafa al Samarai, M.alSamarai@uu.nl, phone: 06 - 253 67 65 

Sponsor: NOW-CW-TOP, Albemarle, Shell, BASF, since October 2011 

Supervisors: Prof. dr. Frank M. F. de Groot and Prof. dr. ir. Bert M. Weckhuysen 

STXM, TXM, EXAFS, STEM(-EELS) 

Crude oil is a mixture of a large number of different hydrocarbons. The sulphur-containing 

molecules are mainly present in the form of a wide range of (substituted) thiols, thiophenes and 

dibenzothiophenes. Deep hydro-desulphurization (HDS) aims to remove sulphur in transportation 

fuels. Here the Co and/or Ni promoted alumina-supported MoS systems form an important class 

2 

of HDS catalytic materials. These catalysts are applied in high-pressure trickle-bed reactors. The 

mechanism for hydrodesulphurization, and the molecular structure and genesis of the active phase 

in supported Co-MoS catalysts have been the topic of extensive research and intense debate over 

2 

the years. 

The combination of a Scanning Transmission X-ray Microscope (STXM) with a dedicated nanoreactor 

cell allows in-situ nanoscale chemical imaging of catalyst materials and related nanomaterials with 

nanometer range spatial resolution. Nanoscale chemical imaging will be applied to the study of 

these catalytic materials, which will be tracked during their catalysis and de-activation conditions. 

The goal of this project is to perform in-situ STXM experiments at 15 bar and visualize the spatial 

distribution of the Co doped MoS slabs during the catalytic reaction. Thusfar it is stil not clear why 

2 

the addition of Co increase the rate of the HDS reaction. It is of great interest to gain information 

about the role of cobalt in this reaction. The Co L edge, and the Al, S, and Carbon K edges are 

within the reach of the soft x-ray regime (200-2500 eV) and can be studied by this technique. 

In addition the carbon K edge measurements are used to trace the position of the reaction products. 

Figure 1: Optical scheme of the STXM imaging mode. 

Synchrotron radiation is used as the x-ray source. A 

zone plate (ZP) in combination with an order-selecting 

aperture (OSA) forms a microprobe, across which the 

specimen is raster-scanned. Signals can be detected 

simultaneously by transmission and emission detectors.


Deactivation of Pt/Al 2 O 3 and PtSn/Al 2 O 3 Catalysts Studied by In-situ Raman 

Spectroscopy 

Jesper Sattler, J.J.H.B.Sattler@uu.nl, phone: 06 - 22736385 

Sponsor: NRSC-C, since February 2010 


Raman Spectroscopy, GC, XAS, STXM 

Catalyst deactivation by means of coke formation is the foremost problem for many petrochemical 

processes. This subject has been intensively studied over the past decades, but is still poorly understood. 

In our work we studied the deactivation of Pt/Al O and PtSn/Al O catalysts by using in-situ 

2 3 2 3 

Raman spectroscopy. [1] By manipulating the laydown of coke more insight on this process was 

obtained. Coke formation was suppressed by adding hydrogen to the feed, while the process was 

enhanced by the addition of propylene. Catalytic data was obtained by gas chromatography (GC). 

It was shown that hydrogen improves the conversion and selectivity of the Pt/Al O catalyst while 

2 3 

the PtSn/Al O catalyst showed an increase in stability. 

2 3 

Raman spectra obtained were deconvoluted in order to obtain detailed information of the separate 

bands, as is shown in Figure 1. [2] Because of this procedure, trends in the band positions, band width 

and ratio between the D1 and G bands were observed. Both bands show a decrease in width as the 

hydrogen content is increased. This implies that less layers of graphene are stacked upon eachother 

as the hydrogen concentration is increased. Furthermore the D1/G ratio increases and the shift 

of the G band to higher Raman shifts indicate an increase of disorder on the coke and a decrease 

of the graphite crystallite size. This shows that by looking in more detail to these spectra, more 

information can be obtained. Further experiments involving XAS and STXM are also performed 

to study the deactivation of these catalysts. 

Figure 1: Normalized Raman spectra of coke deposits formed on a Pt/Al 2 O 3 catalyst using feeds with different ratio’s of 

propane and hydrogen. 

[1] J. Catal. 276, 2010, 268. 

[2] Carbon 43. 2005, 1731. 

61

62 


Electronic and geometric structure determination of ligand-nanoparticle 

interactions 

Matti M. van Schooneveld, M.M.vanSchooneveld@uu.nl, phone: 06 - 22736392 

Sponsor: NWO-CW, since October 2008 

Supervisors: Prof. dr. Frank M. F. de Groot and Prof. dr. ir. Bert M. Weckhuysen 

RIXS, colloidal synthesis, DFT, charge transfer multiplet calculations 

Direct measurement of the electronic structure of chemical bonds formed at a surface is far from 

trivial but important. When it concerns metal catalysis, the electron configuration and electron 

dynamics within the first atomic layers controls to a large extent how molecules adsorb, break 

and form chemical bonds, and eventually desorb. Despite the existence of sensitive surface science 

techniques it remains a challenge to specifically probe the bond between an atom in the first 

atomic layer of a metal system and the atom within the molecule that binds with the metal surface. 

We investigate to what extent resonant inelastic X-ray scattering (RIXS) can probe this bond. 

Experimental 2p3d RIXS on cobalt organometallic complexes has revealed a class of previously 

unobserved Raman features. In combination with time-dependent density functional theory and 

charge transfer multiplet calculations, these features are ascribed to low energy d-d excitations 

in the metal cations of the molecular complexes. Experimental spectra on cobalt and cobaltnickel 

nanoparticles reveal similar Raman features, possibly originating from metal cations in the 

nanoparticle outer atomic layer as a result of the adsorbate binding. Put in a broader context, these 

studies address the question to what extent RIXS can be used for the study of surface metaladsorbate 

interactions.


Surface- and Tip-Enhanced Raman Spectroscopy for the Study of Heterogeneous 

Catalysts 

Evelien van Schrojenstein Lantman, E.M.vanSchrojensteinLantman@uu.nl, 

phone: 06 - 22736375 

Sponsor: NRSC-Catalysis and NanoNextNL, since November 2009 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen and dr. Arjan J.G. Mank 

TERS, AFM, Raman, colloidal synthesis 

Raman spectroscopy is a useful technique in the characterization and identification of molecules 

and solids. It is often used in the field of catalysis research for e.g. online monitoring of catalysts. 

Unfortunately it often gives only a weak signal, unless specific metal nanoparticles are placed in 

close proximity to the studied molecules. The effect of Surface Enhanced Spectroscopy (SERS) 

is most pronounced in Ag and Au nanoparticles with dimensions in the range of 20-100 nm. The 

exact enhancement effect is greatly dependent on the material, size and shape of the nanoparticles. 

In order to successfully employ SERS, it is necessary to choose these properties carefully for the 

required application. 

In the field of microscopy, the SERS-effect can be applied to the tip of an Atomic Force Microscope 

(AFM), creating Tip-Enhanced Raman Spectroscopy (TERS). By coating an AFM-tip with a thin 

layer of Ag, it is possible to perform Raman microscopy with a resolution of 10 nm. [1] This is far 

beyond the wavelength-dependent diffraction limit of light, and it is purely dependent on the size 

of the tip-apex of the AFM-tip. 

TERS will be able to shed light into a wide range of samples within the field of catalysis as 

a microscopic method for heterogeneous catalysts and a small-scale Raman probe for in-situ 

monitored reactions. An example of the last application has been explored with the photo-reaction 

of p-nitrothiophenol (pNTP) to p,p’-dimercaptoazobisbenzene, in which we employed a dualwavelength 

approach to be able to separate measurement and reaction-activation (see Figure 1). 

Figure 1: Schematic overview of a TERS experiment. The object of study is a monolayer of pNTP, assembled on a Au nanoplate. 

The Ag-coated TERS tip acts both as TERS-probe and as the photo-catalyst of pNTP when the sample is illuminated with 

green light. 

[1] J. Raman Spectrosc. 40, 2009, 1343. 

63

64 


Nanoreactors-based Mesoporous Materials: Development and Their Host 

Application for Chiral Organometallic Complexes 

Dr. Mozaffar Shakeri, M.Shakeri@uu.nl, phone: 06 - 22736107 

Sponsor: NRSC-Catalysis, since January 2011 


SEM, N 2 -physisorption, TGA, NMR 

Asymmetric synthesis of chiral compounds by organometallic complexes has attracted significant 

attention in both industry and academia due to their lower dosage and high efficacy in pharmaceutical 

industry and agrochemistry.[1] However, asymmetric synthesis in overall application is limited due 

to difficulty in organometallic complexes separation from the reaction mixture which consequently 

generates economic and environmental problems. Immobilization of chiral organometallic complexes 

in mesoporous materials through chemical bonding and strong ionic interaction has become a most 

often investigated method to overcome mentioned problems. However, those methods often cause 

detrimental changes on the properties of the immobilized complexes.[2] 

In this project we study the entrapment of chiral organometallic complexes in nano-cavities of 

mesoporous materials in which the size of the entrance is smaller than the main pore size (Figure 

1). Entrapment of large complexes can be initiated from diffusion of the precursors inside the pore 

followed by reaction and formation of large complexes that are bigger than the entrance size. For that, 

we firstly synthesize and characterize nano-cavities of mesoporous materials and then employ those 

for entrapment of chiral organometallic complexes.[3] The obtained organometallic complexes/ 

mesoporous materials then will be used in asymmetric synthesis of chiral alcohols. 

Figure 1: Schematic overview of an entrapped organometallic complex in nanocavities of mesoporous material. 


[2] Chem. Rev. 102, 2002, 3495. 

[3] J. Phys. Chem. B 106, 2002, 5873.

Solid acid catalysts for transesterification and esterification 

Daniel Stellwagen, D.R.Stellwagen@uu.nl, phone: 06 - 22736372 

Sponsor: Catchbio, since July 2010 


Inorganic synthesis, Organic synthesis, GC, XRD 


Biodiesel mainly contains fatty acid methylesters (FAME), which are obtained by transesterification 

of triglycerides using methanol. In order to facilitate the use of low grade triglyceride feeds (e.g. 

waste cooking oil, animal fat, or non-edible oils), there has been increasing interest in heterogeneous 

acid catalysts for the biodiesel production process. [1] While promising results have been reported 

for various mixed metal-oxide super acids (e.g. tungstated zirconia), such materials have yet to attain 

the activity of their protic acid catalysts counterparts. 

The majority of the literature on acidic heterogeneous catalysts for transesterification focuses on 

sulfonated materials, either metal-oxide (e.g. sulfonated zirconia) or carbon (e.g. ‘sugar catalyst’ [2]) 

based. While high initial activities have been reported for almost all of these materials, a universal 

problem seems to be their poor stability over multiple runs due to leaching of the sulfonic acid 

(-SO H) groups. 

3 

The current focus of this project is developing novel acidic ordered carbon materials with high 

activity and stability in the biodiesel production process. Another area of interest is the synthesis 

and testing of modified tungstated zirconia. In particular the behavior and influence of the various 

tungsten phases on the performance of the final material is studied. 

Figure 1: Schematic representation of Transesterification. 

[1] Green Chem. 11, 2009, 1285; Ind. Eng. Chem. Res. 44, 2005, 5353. 

[2] Nature 438, 2005, 178. 

65

66 


Catalyst Development for the Production of Cyclic Monomers Derived from 

Glycerol and Fatty Acid Substrates 

Joseph Stewart, J.A.Stewart@uu.nl, phone: 030 - 253 36 35 

Sponsor: BPM, since September 2010 


NMR, GC, LC, XRD 

With the increasing levels of bio-diesel production, there is more emphasis being placed on utilising 

the by-products of this process. It has been shown previously that glycerol, a by-product of biodiesel 

production, can be converted into glycerol carbonate, which can be used as a solvent, an 

additive and as chemical intermediates. One popular area of research in recent years hasbeen 

bio-based polymers, such as polylactic acid (PLA), polyethylene glycol (PEG) and polycaprolactone 

(PCL). Not only do these type of polymers combine the advantage of using naturally occurring 

substrates, but they can also degrade to harmless substrates as well, which can either be recycled, 

reused or returned to the environment without polluting it. 

It is with these two types of research in mind that this project investigates the synthesis of monomers 

from glycerol derivatives and fatty acid-derived building blocks for the production of a new range 

of bio-based polymer systems. Research will be carried out investigating both heterogeneous and 

homogeneous catalytic systems to tune the activity and selectivity of the system as well as the ability 

to recycle the catalyst itself. 

These processes will be analysed by various techniques including NMR, GC, LC and LC-MS. The 

catalytic systems themselves will also be extensively characterised by numerous techniques, so that 

the system can be optimised and fully understood.


Branched alcohols from (bio) alcohols via gas phase Guerbet reaction 

Dr. Selvedin Telalović, S.Telalovic@uu.nl, phone: 06 - 22736090 

Sponsor: CatchBio, since December 2010 

Supervisors: Prof. dr. ir. Krijn P. de Jong, dr. Johannes H. Bitter and dr. Jaap W. Van Hal 

N 2 -Physisorption, XRD, GC, TEM 

The Guerbet reaction converts lower (bio) alcohols to higher alcohols. This is an important step 

in the valorization of (bio) ethanol. The reaction is thought to proceed via the dehydrogenation of 

the alcohol, the condensation of formed aldehyde or ketone, the dehydration of the condensation 

product and subsequent hydrogenation of the double bond and the aldehyde/ketone group (see 

Figure 1). One of the aims of the project is to design a catalyst for challenging reaction network 

with many intermediate products. 

Figure 1: Guerbet Reaction. 

Industrial production of Guerbet alcohols employs homogeneous catalysts with disadvantages 

as large amounts of spent catalyst/ton product and high costs associated with product and waste 

treatment. By employing heterogeneous catalyst we aim at increasing the efficiency and insight in 

the production of Guerbet alcohols. 

67

68 


Direct production of lower olefins from synthesis gas using iron based catalysts 

Hirsa Torres, H.M.Torresgalvis@uu.nl, phone: 06 - 22736364 

Sponsor: ASPECT-ACTS since October 2007 


TEM, XRD, GC, Catalytic testing 

The Fischer-Tropsch to olefins (FTO) process is a direct route for the conversion of synthesis gas 

= = into light olefins (C -C4 ). The FTO process has to be carried out at high temperatures in order 

2 

to drive product selectivity to short chain hydrocarbons. Under these conditions, the methanation 

reaction is kinetically favored resulting in a detrimental effect on product selectivity. 

Many studies have been carried out to find a promoter or a combination of promoters that allow 

an important decrease in methane formation and that could improve the selectivity towards lower 

olefins simultaneously. [1] It has been reported that promoted bulk iron catalysts modified with 

sodium and/or sulfur can achieve methane selectivities as low as 10%C and C -C olefins selectivities 

2 4 

of about 35%C. [2] However, up to now, there is no industrial application of these catalysts probably 

due to their low mechanical stability. 

Bulk iron catalysts that are subjected to the very demanding conditions of FTO tend to disintegrate 

as a result of carbon lay-down. [3] An improvement in the mechanical stability of iron-based catalysts 

has been achieved by dispersing iron on an inert support that will provide mechanical anchoring 

for the promoted Fe nanoparticles while allowing the formation of the carbidic active phase. [4] 

Catalysts with high selectivity towards lower olefins, low methane production and excellent 

mechanical stability have been synthesized by incipient wetness impregnation of ammonium iron 

citrate or iron nitrate on α-Al O . The sodium and sulfur promoters were incorporated by co- 

2 3 

impregnation of aqueous solutions of sodium citrate (or nitrate, depending on the iron precursor) 

and iron or ammonium sulphate. 

Fe/α-Al 2 O 3 fresh Fe/α-Al 2 O 3 spent Fe-Ti-Zn-K fresh Fe-Ti-Zn-K spent 

Figure 1: TEM micrographs of fresh and spent iron catalysts: A,B: supported, C,D: bulk. 

[1] U.S. Patent No. 4564642, 1986. 

[2] Int. Pat. Appl. No. WO 2010066386 A1, 2010. 

[3] Appl. Catal. A 133, 1995, 335. 

[4] Int. Pat. Appl. No. WO2011049456 A1 2011.


Sustainable Production of Novel Polyglycols from Renewable Resources 

Dr. Qingqing Wang, Q.Wang1@uu.nl, phone: 06 - 17167578 

Sponsor: ACTS-ASPECT, since 2009 


NMR spectroscopy, GPC, IR spectroscopy, Elemental Analysis (ICP) 

Polyglycols or polyether polyols are very important bulk chemicals which has shown a wide variety 

of applications in making performance polymers, as additives to cosmetics and medicines. The 

polyether polyols are commercially manufactured from petrochemicallly-derived alkylene oxides, 

such as ethylene oxide and propylene oxide. In the last decades, a large scale of glycols were generated 

in industrial fermentation process, for example, over 100 million pounds of 1,3-propanediol per 

year. Sustainable production of polyether polyols from the renewable resources is an interesting area, 

which shows commercial and environmentally benign siginificancy. Currently, the commercialized 

polymer Sorona® has used Bio-PDO as its component. [1] In order to dismiss the unfriendly effects 

on enviroment as well as decreasing the cost of traditional homogeneous catalysts in the reaction, 

inexpensive, reusable, and stable catalysts will be investigated to accelerate the polyetherification 

process. Therefore, the aim of this project is to develop a process that directly converts renewable 

glycols to polyether polyols with heterogeneous catalysts. 

Now, the reaction conditions and the setup were optimized for the polyetherification of 1,3-propylene 

glycol and 1,6-hexylene glycol. Sulfuric acid was used as the catalyst. [2] Polymers were analyzed 

by NMR and GPC, and volatile products or distilled reactants were identified by GC, GC-MS. 

Polymers of 1,3-propylene glycol with Mn up to 2964 and a degree of polymerization 26 were 

obtained. Polyether polyols from 1,6-hexylene glycol shows Mn up to 1344 and a degree of 

polymerization of 14. In another aspect of the project, now, the research focuses on the study of 

heterogeneous acid catalysts for the polyetherification of 1,3-propylene glycol. Sulfonated carbon 

acid catalysts are one kind of the most promising choices, and the carbon support is a product from 

hydrothermal process of sucrose, which is also a renewable resource. Polymers of 1,3-propylene 

glycol with Mn up to 1273 and a degree of polymerization of 17 were obtained in the reaction 

catalyzed by the carbon based catalyst. A screening of various solid acid catalysts will be tested in 

the polyetherification process of 1,3-propylene glycols, and then for the reaction of a wide range 

of other biomass derived glycols. 

Table 1: Mw and Mn results of polyether polyols from 1,3-PDO. 

Samples Conditions Mn(NMR) DP Uns-end Mw Mn(GPC) PD 

PS6-2 Ar, 185°C, 26h, H SO 2 4 1472 25 515 4644 2389 1.94 

PS8 Ar, 185°C, 26h, H SO 2 4 1507 26 498 6021 2964 2.03 

PC2 Ar, 185°,C 26h, C-HSO3 961 17 492 2139 1273 1.68 

[1] Green Chem. 12, 2010, 1410. 

[2] US 6977291 B2, 2005. 

69

70 


Use of Spectroscopy to Optimize the Zeolite-catalyzed Synthesis of Branched 

Fatty Acids for Large-Scale Manufacturing 

Dr. Sophie Wiedemann, S.C.C.Wiedemann@uu.nl, phone: 06 - 22795021 

Sponsor: Croda, since January 2011 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen and dr. Pieter C. A. Bruijnincx 

UV-VIS spectroscopy, FTIR, TGA 

Branched-chain fatty acids (bc-fas) are used extensively as a lipid raw material for production of 

a.o. lubricants, cosmetics and surfactants, where they provide a unique combination of excellent 

thermal stability and low-temperature liquidity. The current commercial process for making bc-fas 

(starting with oleic acid) yields only 50% or less, the balance of the reaction products being mainly 

polymerised acids. Montmorillonite clay is used as heterogeneous catalyst. [1] 

Isomerisation of oleic acid using zeolites represents the most promising route to isolation of bc-fas 

in high yields and has been investigated by several groups. 

Recently, a research group at the USDA reported a step change in both yield and selectivity using 

commercial zeolites from the ferrierite group. [2] Selectivity has been further improved by the use 

of a Lewis base as co-catalyst. [3] However, the cost of the ferrierite, and its loss of activity with 

successive re-use, still makes it an uneconomic option for large-scale application in price-sensitive 

markets. 

Our research is aimed at understanding the specificities of ferrierite in bc-fas processing with regard 

to both activity and selectivity by the use of various spectroscopy techniques. In a first phase, we 

are investigating the deactivation of the catalyst during isomerisation. The nature and formation 

rate of coke is studied by the powerful combination of UV-VIS and FTIR. 

[1] J. Am. Oil Chem. Soc. 62, 1985, 888; J. Mol. Catal. A: Chemical 134, 1998, 159. 

[2] Eur. J. Lipid Sci. Techn. 108, 2007, 214. 

[3] Patent US2011/0263884 A1.


Focused Ion Beam-Scanning Electron Microscope Applications on Zeolite 

Materials 

Matthijs de Winter, D.A.M.deWinter@uu.nl, phone: 030 - 253 30 05 

Sponsor: NRSCC 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen, Prof. dr. Martyn R. Drury and dr. Jan Andries Post 

FIB-SEM, EBSD 

The FIB-SEM (Focused Ion Beam – Scanning Electron Microscope) enables to produce micrometer 

sized cross sections in virtually any material. Subsequently the SEM can be used to investigate the 

cross section in-situ, using a range of detectors. [1] As both the ion beam and electron beam consist of 

charged particles, non-conductive samples proof to be difficult to work on. This research is focusing 

on solving charge related problems to be able to conduct research on non-conductive samples. 

Possible solutions vary per type of sample and per type of SEM investigation. A simple solution is 

using a sputter coater to deposit a thin (3 nm) layer of conductive metal on the surface. However 

Electron BackScatter Diffraction (EBSD), which is a surface technique to measure the crystallographic 

orientation, doesn’t allow any coating. Alternatives are investigated, such as defocusing (spreading 

the charge), using the FIB to locally remove the coating (charge can escape via the coating nearby) 

or using gas to dissipate the charge (taken up by ionized molecules). These techniques are applied 

to large zeolites model systems (such as ZSM-5) and revealed the internal intergrowth structure. [2] 

Another application is called Slice and ViewTM . The FIB removes thin consecutive slices and the 

SEM images the resulting cross sections, resulting in a stack of images which can be processed into 

a 3D representation of the analyzed volume. This technique has been applied to steamed ZSM-5 

and revealed an internal architecture-dependence of mesoporosity on intergrowth structures. [3] 

Future research concentrates on applying similar techniques to entire FCC particles. 

Top figure: A schematic representation of the Slice and View setup, using the FIB 

to mill thin slices and the SEM to image the cross section. The SEM images can 

be post-processed into a three dimensional representation of the mesopores, 

as shown in the figure on the right. 

[1] MRS Bulletin 32, 2007. 

[2] Angew. Chem. Int. Ed. 47, 2008, 5637; Nat. Mater. 8, 2009, 959. 


71

72 


Catalytic Routes for the Valorization of Humin By-products Formed during 

Biomass Processing 

Ilona van Zandvoort, I.vanZandvoort@uu.nl, phone 030 - 253 67 65 

Sponsor: CatchBio, since December 2009 

Supervisors: Prof. dr. ir. Bert M. Weckhuysen and dr. Pieter C. A. Bruijnincx 

FTIR, Catalytic testing, GC, HPLC 

The majority of the chemicals and fuels are currently derived from fossil crude oil. Limited availability 

of crude oil and current high prices makes it mandatory to look for sustainable feedstock for future 

generations. Biomass is the only renewable option for the manufacture of carbon containing (bulk)chemicals. 

Carbohydrates, the major components of lignocellulosic biomass, have been identified as 

important feedstock for biobased (bulk)-chemicals. A wide variety of intermediates such as HMF, 

sorbitol, lactic acid, succinic acid and levoglucosan can be synthesized from carbohydrates. [1] 

A major issue when using carbohydrates is the formation of large amounts of low value carbonaceous 

waste by-products known as humins. [2] To make carbohydrate-based routes to sustainable chemicals 

economically more viable, it is essential to valorize these humins. In this project we aim to valorize 

the humin by-product by converting it into valuable chemicals. 

Figure 1: Formation of humin by-products during biomass processing. 

[1] Clean 26, 2008, 641. 

[2] Tetrah. Lett. 26, 1985, 2111; Chem. Eng. Res. Des. 84, 2006, 339.

Electron tomography study of mesoporous zeolites 

Jovana Zečević, J.Zecevic@uu.nl, phone: 06 - 22736107 

Sponsor: Total 2009-2011, NRSC-C 2011-2013 


Electron tomography (3D-TEM), TEM, N 2 -physisorption, XRD 


Increasing demands of refining and petrochemical industries led to tremendous developments in a 

field of catalysis. Novel synthesis routes and post-synthesis treatments have been introduced in order 

to obtain more active and selective catalysts. To understand the properties of these materials, detailed 

structural analysis is needed. Electron tomography proved to be an excellent tool for elucidating 

the complex structural features in three dimensions on a nanometer scale resolution. 

This project is focused on investigating structural properties of mesoporous zeolite Y, which is 

widely used as catalyst for cracking and hydrocracking processes. In order to increase the activity 

by increasing the reactive surface area, mesopores (2-50 nm) are commonly introduced in zeolite 

Y. Moreover, mesopores act as a “highways” for diffusing molecules of reactants and products. 

However it is not solely the presence of this mesopores, but also the shape size and connectivity 

that will determine the effectiveness of mass transfer through the zeolite crystals. Thanks to electron 

tomography, we are able to image these complex mesopore networks (Fig. 1a) in all three dimensions. 

Furthermore, in combination with image processing, various properties of mesopores can be defined 

and measured, such as constriction of the pores (Fig. 1b) and their tortuosity. 

Figure 1: Characterization results of Y zeolite CBV760 sample a) Volume and isosurface rendered reconstruction of 

mesoporous zeolite Y particle b) discriminated opened (green) and closed (red) mesopores, where open mesopores are 

the ones that can be reached from the outer surface through the mesopore network, while the closed ones can be reached 

only via micropores. 

73

74 

Inorganic Chemistry and Catalysis

Nanophotonics 


Nanophotonics 

75

76 

Nanophotonics 

Spin drag in a Bose gas 

Pieter Bons, P.C.Bons@uu.nl, phone: 030 - 253 29 16 

Sponsor: FOM 

Supervisor: Prof. dr. Peter van der Straten 

Laser cooling, Magnetic traps, Optical Tweezers 

Spin currents, well known in spintronics, are subject to strong damping due to collisions between 

spin species, a phenomenon known as spin drag. We have performed spin drag experiments for 

ultra-cold atoms[1]. We prepare an equal mixture of pseudo spin up and down atoms and apply a 

force on one of the species. As a result a constant drift velocity between the spin species develops, 

which is a measure of spin drag. Close to the phase transition to BEC we observe a strong increase 

of spin drag due to Bose stimulation, in agreement with recent theory[2], acting as a precursor 

for Bose-Einstein condensation. Our results pave the way for studies of transport properties of 

degenerate bosons that are very different from fermionic systems. 

Figure 1: Two ultra-cold atomic Bose-gases of different spin. The line profiles show an asymmetry and a relative displacement 

of the centers of mass (vertical lines), which are indications of spin drag. 

[1] S.B. Koller, A. Groot, P.C. Bons, R.A. Duine, H.T.C. Stoof, P. v.d Straten, Spin drag in a Bose Gas (submitted). 

[2] R.A. Duine, H.T.C. Stoof, Spin Drag in Noncondensed Bose Gases, PRL 103, 170401 (2010).

Exploiting plasmonic effects in ultra-thin amorphous silicon solar cells 

Lourens van Dijk, l.vandijk@uu.nl, phone: 030 - 253 25 09 

Sponsor: NanoNextNL, since August 2011 

Supervisors: Prof. dr. Ruud E.I. Schropp, dr. M. Di Vece 

Cluster Deposition, Finite Difference Time Domain (FDTD) modeling 

Nanophotonics 

This research is part of the quest to develop photovoltaic cells that generate electricity at low cost 

per kWh. The current solar cell market is predominantly based on cells made of crystalline silicon 

wafers. Over the years the cost per Watt-Peak has been reduced significantly, partially by reducing 

the wafer thickness from around 300-400 to ~200 μm. The potential for further reducing the 

costs of these cells is however limited because of the high material purity that is required for these 

diffusion-type solar cells. The absorber layer thickness can be reduced three orders of magnitude 

using amorphous silicon (a-Si) because of its direct bandgap nature, leading to relatively high 

absorption coefficients. Further cost reduction is achievable by reducing the fabrication time by 

both faster deposition techniques and an even further reduced cell thickness. 

Generally, cells become more transparent as the thickness is reduced, and thus the total absorption 

decreases. Metal nanostructures can be integrated to prevent this deterioration of the optical 

performance. These structures increase the optical path length in the cell (light scattering, plasmonic 

enhancement, and light trapping). An advantage of these cells is that the electrical properties improve 

as the generated charge carriers have to travel less far. 

In our laboratory a novel nanocluster deposition system is used to deposit metal nanoclusters (1-50 

nm). Using this system metal nanoclusters with a tunable monodisperse size (10%) can be deposited 

at an arbitrary position in the cell. From the theory it is expected that these particles behave as 

plasmonic scatterers. Placing them on top of a solar cell is expected to result in a reduced reflectance 

and scattering of light under high angles in the cell. This effect is caused by the collective movement 

of the free electrons of the metal nanoclusters. It is expected that by exploiting these plasmonic 

effects we can make good quality thin film silicon solar cells with an absorber layer less than 100 

nm thick. 

Figure 1: Graphical representation of a photovoltaic cell with metal nanoparticles on top. Light enters the cell perpendicular 

to the surface and propagates mainly in the lateral direction through the cell. 

77

78 

Nanophotonics 

Novel Multifunctional Emitters for Heterojunction Solar Cells 

Henriette Gatz, H.A.Gatz@uu.nl, phone: 030 - 253 88 56 

Sponsor: Technology Foundation STW, since October 2011 

Supervisors: Prof. dr. Ruud E.I. Schropp and dr. Jatin K. Rath 

HWCVD, VHF PECVD, Reflection/transmission spectroscopy, Conductivity measurements 

Silicon heterojunction solar cells hold the potential for high efficiency devices at low manufacturing 

costs. Their main part consists of amorphous silicon layers (a Si:H) deposited on top of a crystalline 

silicon wafer (c-Si). 

The left schematic structure of Figure 1 shows the different layers of a silicon heterojunction 

(SHJ) cell. Our research focusses on the acceptor doped (p-type) thin a-Si:H emitter layer and the 

Transparent Conductive Oxide (TCO) layer. The TCO layer not only acts as a perfect window 

for the incoming light, but also provides a sufficient conductivity to transport the current to the 

front terminal of the cell. 

Commonly used TCOs have several drawbacks such as a narrow range of refractive index and 

work function. This does not allow for much tuning in order to optimize the carrier collection 

and transport. Therefore, we aim to develop a novel two-phase transparent doped nanocrystalline 

silicon oxide (nc-SiOx:H) by chemical vapor deposition to replace the TCO layer. The SHJ cell 

structure and its fabrication process should thereby be simplified. 

As indicated in the right schematic structure of Figure 1, this new layer ideally combines the 

properties of the emitter layer, the TCO, and the antireflective function (AR). 

By modifying the dopant concentration and the size of the silicon nanocrystals in the SiOx:H 

matrix the transparency and conductivity of the layer can be controlled. A proper band alignment 

can be achieved by tuning the work function of the material whereas the refractive index will be 

fine-tuned for an optimum anti-reflective coating. 

Figure 1: Illustration of the different layers of a silicon heterojunction solar cell (drawn not to scale). Left: Current 

heterojunction solar cell. Right: Proposed new heterojunction solar cell. The emitter, conduction, and antireflective function 

are combined in the novel layer.

First and second sound in a weakly interacting Bose gas 

Alexander Groot, a.groot@uu.nl, phone: 030 - 253 28 01 

Sponsor: FOM, since Dec 2009 

Supervisor: Prof. dr. P. van der Straten 

AAS, Laser Cooling, Magnetic traps, Optical tweezers 

Nanophotonics 

First and second sound are the hallmarks of two fluid hydrodynamics. These sound modes are mainly 

density modulations in the non-condensed and condensate fractions of an ultra-cold bosonic gas. 

There is a weak coupling between first and second sound, leading to an avoided crossing at very 

low temperatures. To investigate the dispersion relation of these modes, two approaches are followed. 

First, a dimple is made in the potential creating a travelling sound wave. In a second experiment, 

a standing sound wave is induced by periodically modulating the trapping potential. From these 

experiments the speed of sound and therefore the dispersion relation is extracted using phase 

contrast imaging and singular value decomposition. 

Figure 1: Phase contrast images of standing sound waves. 

79

80 

Nanophotonics 

Narrow bandgap materials for thin film multijunction solar cells 

Xin Jin, X.Jin@uu.nl, Phone: 030 – 254 3165 

Sponsor: UU/CSC since 01-2009 

Supervisor: Prof. dr. R.E.I. Schropp 

Hot-wire CVD, PECVD, Electrical conductivity and activation energy, FTIR 

Narrow bandgap silicon based thin film materials are investigated worldwide for application in 

tandem and triple junction solar cells. Nanocrystalline silicon has a band gap of 1.1 eV, which makes 

a perfect combination with the 1.8-eV band gap of a Si:H, but the time needed for deposition of a 

sufficiently thick layer is a drawback. We study Hot Wire CVD as a means to increase the deposition 

rate of these layers, as well as to create alternative layers that can be deposited at least 10 times as fast. 

Simultaneously, optimized deposition parameters will be developed to obtain thinner active layers. 

One alternative is to alloy Si thin films with germanium (Ge). Such thin films can be made an order 

of magnitude thinner while keeping similar total absorption. Depending on the concentration of 

Ge, this allows continuous variation of the band gap, from 1.8 eV down to even below 1.1 eV (for 

nanocrystalline SiGe). Multijunction solar cells (see the schematic figure below), with a SiGe:H 

or nc SiGe:H employed as the absorber layer in the middle and/or bottom cells, utilize a broader 

solar spectral range compared to single junction silicon based solar cells. To prepare such cells by 

HWCVD is of interest because it is an ion-free, low-damage growth process under high atomic 

hydrogen flux, which facilitates the deposition of relatively low-defect alloy layers. Moreover, due 

to the efficient catalytic decomposition of the feedstock gases at the hot transition metal wire, there 

is good potential for high deposition rate. 

The aim of this research is to achieve bandgap graded a-SiGe and nc-SiGe based thin film solar 

cells by hot-wire CVD, and compare these with pure nc-Si:H, which is the more common narrowbandgap 

material. The optical, electronic, and structural properties of SiGe:H i-layers will be 

evaluated and implemented in highly efficient multijunction solar cells. 

Figure 1: Schematic tandem solar cell concept.

Nanophotonics 

Thin film silicon solar cells on cheap flexible and micro-V structured substrates 

Minne de Jong, M.M.deJong@uu.nl, 030 - 253 32 63 

Sponsor: AgentschapNL, EOS programma 

Supervisors: Prof. dr. R.E.I. Schropp and dr. J.K. Rath 

VHF-PECVD, Mass-spectrometry, Retarding Field Ion Energy Analysis, AFM 

Thin film silicon solar cells can be deposited on many types of substrates, which include plastics and 

paper-like foils. To be able to do this, deposition temperatures will have to be decreased drastically. 

The challenges encountered when decreasing the deposition temperature are (i) deterioration of 

the optoelectronic properties of the layers, (ii) severe mechanical stress, which results in curling 

of the substrates or the layers peeling off, and (iii) the formation of dust in the plasma, which can 

result in electronic defects and shunting of solar cells. The aim of this research is to obtain a better 

understanding of the processes involved and elimination of these problems. For this we monitor 

the plasma using Optical Emission Spectroscopy, Retarding-Field Ion Energy Analysis and Energy 

Resolved Mass spectrometry and correlate the plasma properties to the layer quality. 

In collaboration with the Wageningen UR Glastuinbouw (WUR) we develop solar cells on hot 

embossed pyramid-like structured polycarbonate substrates. WUR performs research on structured 

plastics for the design of greenhouse roofs that are extremely transparent for sunlight. As a spin off, 

we use the same structures to develop substrates that can provide an optimal light confinement in a 

thin film silicon solar cell. We investigate layer growth on these structures and optimize the shape and 

size of the structure. Thus far, we have succeeded in fabricating amorphous silicon (a-Si) solar cells at 

130°C with a conversion efficiency of around 8%. At this low deposition temperature amorphous/ 

microcrystalline tandem cells were made with an efficiency of 9.5%. On plastic (polycarbonate), 

using a 400 nm base pyramidal structure, we obtained a conversion efficiency of 7.4%. This is the 

highest reported efficiency of p-i-n a-Si cell on a cheap plastic substrate. Further research will be 

done to develop nanocrystalline and tandem cells on structured and unstructured plastics. 

Figure 1: I-V curves for low (

82 

Nanophotonics 

Nanorod Solar Cells with Ultrathin a-Si:H Absorber Layers 

Yinghuan Kuang, y.kuang@uu.nl, phone: 030 - 253 29 64 

Sponsor: China Scholarship Council (CSC), since October 2009 

Supervisor: Prof. dr. Ruud E.I. Schropp 

HWCVD, PECVD, aqueous chemical growth, HRSEM, XRD 

In solar cells, the absorber layer must be optically thick to capture a sufficient fraction of incident 

photons but must also be sufficiently thin to enable efficient minority carrier collection [1-2]. In 

order to eliminate the trade-off, we propose a novel third generation solar cell concept here, which 

employs an architecture of zinc oxide nanorod arrays coated by an ultrathin a-Si:H n-i-p junction to 

form a nanorod three dimensional (nano-3D) solar cell (figure 1a). We experimentally demonstrated 

the photovoltaic performance of the nano-3D solar cells [3-4]. Density-controlled ZnO nanorod 

arrays were synthesized by aqueous chemical growth at 80°C (figure 1b). The microstructure of the 

completed nano-3D solar cells is shown in figure 1c and d. With an ultrathin absorber layer of only 

25 nm, an efficiency of 3.6%, significantly higher than values achieved for the planar or even the 

Asahi randomly textured counterparts with a three times thicker (~75 nm) a-Si:H absorber layer. By 

increasing the absorber layer thickness in the nano-3D solar cells from 25 nm to 75 nm, the efficiency 

improved from 3.6% to 4.1%, as shown in figure 2a. Nano-3D solar cells demonstrated higher external 

collection efficiencies than the flat and the texture counterparts, as shown in figure 2b. 

Figure 1. The nano-3D solar cell: (a) Cross-sectional schematic structure of the nanorod solar cell. (b) Tilted HRSEM top 

view of the as-prepared ZnO nanorods on a flat ZnO pre-coated glass substrate. Cross-sectional view of the nanorod solar 

cell with 25 nm (c) and 75 nm (d) thick a-Si:H absorber layers. All scale bars are 500 nm. 

Figure 2. Photovoltaic performance of the four kinds of studied solar cells. (a) J-V measurements of the flat cell (F75), the texture 

cell (T75) and the nanorod cell with 25 nm (NR25) and 75 nm (NR75) thick i-layers. (b) The corresponding spectral response curves. 

[1] H. A. Atwater and A. Polman, Nature Mater., 9, 205 (2010). 

[2] B. M. Kayes, H. A. Atwater and N. S. Lewis, J. Appl. Phys., 97, 114302 (2005). 

[3] Y. Kuang, K. H. M. van der Werf, Z. S. Houweling and R. E. I. Schropp, Appl. Phys. Lett., 98, 113111 (2011). 

[4] Y. Kuang, K. H. M. van der Werf, Z. S. Houweling, M. Di Vece and R. E. I. Schropp. Non-Cryst. Solids (2011), doi:10.1016/j. 

jnoncrysol.2011.11.021 (in press).

Nanophotonics 

Role of ion energy and gas phase transients in the plasma on the interface 

of c-Si and a-Si(H) 

Kees Landheer, c.landheer@uu.nl, phone: 030 - 253 88 56 

Sponsor: STW, since November 2011 

Supervisors: Dr. Jatin K. Rath and Prof. dr. Ruud E.I. Schropp 

PECVD, OES, SDPC, QSSPC 

In this project we want to increase the current energy efficiency of heterojunction silicon solar cells 

in Europe. The record efficiency today is 23.7% and has been achieved by the Japanese company 

Sanyo with their HIT (heterojunction with intrinsic thin layer) solar cell [1]. The best efficiency 

achieved at Utrecht University is 16.7% without the use of light trapping geometries. All efficiencies 

exceeding 20% have been achieved on n-type float zone (FZ) c-Si wafers [2] that are textured to 

enhance light trapping. The fabrication of silicon heterojunction (SHJ) solar cells [1,2] starts with 

a plain crystalline wafer. The functional device is obtained by depositing thin films on both sides 

using plasma enhanced chemical vapor deposition (PECVD). We investigate the relation between 

plasma properties and the c-Si / a-Si:H and a Si:H/ a-Si:H(n/p) interfaces, both on flat and textured 

silicon wafers. To this end, the plasma is studied by optical emission spectroscopy (OES) and an 

ion energy analyzer. OES reveals the constituents of the plasma. With the ion energy analyzer the 

influence of ion impact energies on the formation of interface defects (i.e. silicon dangling bonds) is 

studied. We are especially interested in the influence of the instabilities at the initial transient plasma 

state on the formation of the interfaces and we will study this by experiments and simulations. This 

is important because the crucial layers are often less than 5 nm thick. Subsequently, we study the 

interface ex situ a.o. with infrared spectroscopy. The recombination channels created by the defects 

will be studied a.o. by spin dependent photoconductivity (SDPC) and life-time measurements, such 

as quasi transient mode (QTMPC) and quasi steady state photo conductance (QSSPC). 

Figure 1: The configuration of the HIT solar cell and its band diagram [3]. 

[1] T. Kinoshita et al., The approaches for high efficiency hit solar cell with very thin (< 100 µm) silicon wafer over 23%, 26th Eur. Ph. 

Sol. En. Conf., Sept 5 and 6, 2011. 

[2] Jan-Willem Schüttauf, Amorphous and crystalline silicon based heterojunction solar cells, PhD Thesis Utrecht University (2011). 

[3] http://pvlab.epfl.ch/heterojunction_solar_cells, visited January 5, 2012. 

83

84 

Nanophotonics 

Trapping a single atom with a fraction of a photon 

Arjon van Lange, A.J.vanLange@uu.nl, phone: 030 - 253 28 01 

Sponsor: FOM, since May 2011 

Supervisor: Dr. Dries van Oosten 

Laser cooling, band structure calculations, SNOM, optical tweezers 

Light-matter interactions become increasingly more important. Already, they determine how we 

perceive the world. In the future photonics is expected to succeed electronics, because photons are 

simply faster than electrons. The emission and absorption of light is inherently quantum mechanical, 

because transitions between quantum eigenstates of atoms are involved. The quantum nature of 

light becomes apparent in an optical cavity. Therefore, the simplest system in which to investigate the 

quantum nature of light-matter interaction, is an atom interacting with light inside an optical cavity. 

We trap an atom in the light field of a photonic crystal nanocavity. The mode volume of the cavity 

is comparable to the polarization volume of the atom. Therefore the proximity of an atom changes 

the cavity resonance frequency. In case of fixed frequency laser pumping of the cavity, the distance of 

the atom to the cavity affects the cavity light intensity and thereby the optical force on the atom. The 

atom will be trapped at ~ 100 nm from the surface for proper choice of frequencies. Remarkably, 

the light intensity required to trap the atom corresponds to only a fraction of a photon [1]. 

In the experimental setup (figure 1a) a cold rubidium atom is trapped above the surface of a 

nanocavity in a photonic crystal waveguide. Calculations on the photonic crystal waveguide 

cavity resonance frequency, mode profile and quality factor are performed with the MPB (MIT 

photonic band) package and Meep (MIT Electromagnetic Equation Propagation) package, an 

FDTD simulation package. The photonic crystal will be produced using e-beam lithography and 

characterized in a scanning near-field optical microscope. 

The rubidium atoms are laser-cooled to a temperature below 50 μK. After evaporative cooling in a shallow 

yet tight optical dipole trap, the cloud of remaining atoms is transported to the sample by moving the 

focus of the optical dipole trap. When the optical power of the dipole trap is lowered, atoms can spill out 

of the trap and into the evanescent field of the cavity. As a result, the transmission of the cavity changes. 

By monitoring the transmission the dynamics of the cavity-atom system can be followed. 

Figure 1: (a) Illustration of the experimental setup. A rubidium atom is trapped in the evanescent field of the cavity in a 

photonic crystal bridge waveguide. The optical dipole trap (vertical red beam) is used to transfer atoms to the cavity. (b) 

Schematic representation of the atom-cavity system. The atom and the cavity are coupled by a vacuum Rabi frequency g(z) 

which depends on the atom-cavity separation z. The maximum vacuum Rabi frequency g ≈ 2π × 18.5 GHz. The spectral 

max 

linewidth of the cavity is γ ≈ 2π × 3.85 GHz and of the atom γ ≈ 2π × 5.89 MHz. 

c a 

[1] D. van Oosten and L. Kuipers, Phys. Rev. A 84, 011802(R) (2011).

Nanophotonics 

Development of intermediate reflectors for high performance tandem solar 

cells 

Dr. Oumkelthoum Mint Moustapha, O.MintMoustapha@uu.nl, phone: 030 - 253 88 56 

Sponsor: EU FP7 project Helathis, since October 2011 


VHF PECVD, Conductivity measurements, IV measurements, Raman spectroscopy 

Light management is a major key for the improvement of thin film solar cells. Tandem solar cell 

designs, which aim at absorption of a wide part of the solar spectrum, have proven their ability to 

improve the device efficiency [1]. 

As shown in Figure 1, a thin film silicon tandem structure consists of an amorphous silicon cell 

(top cell) connected in series to a microcrystalline silicon cell (bottom cell), respectively converting 

high and low energy photons to current. In order to minimize the light-induced degradation, 

the amorphous layer should be kept as thin as possible. Which leads to an inbalance between the 

currents of the top and bottom cells. 

In order to increase the current of the thin top cell, for proper current matching of the component 

cells, an intermediate reflector (IR) layer that increase the amount of the absorbed light by the top 

cell, can be introduced within the structure (see Figure 1). Such layer should meet the following 

requirements: it should reflect high photon energy light back into the top cell; transmit the light 

needed for the bottom cell; conduct the current between the two cells. 

Different approaches of IR will be investigated within this project [2]. For example: 

• Doped microcrystalline silicon oxide: a mixed-phase material that can combine the required 

optical and electrical properties depending on its depositions conditions 

• 1D photonic layers (distributed Bragg reflectors:DBR) based on Si and ZnO: a stack comprising 

alternating ZnO and Si layers can be designed to possess the desired properties. 

Figure 1: Schematic diagram of silicon tandem cell. 

[1] M.Yoshimi et al, High efficiency thin film silicon hybrid solar cell module on 1m2-class large area substrate, in: Proceedings of 

the Third World Conference on Photovoltaic Energy Conversion, Osaka, Japan, 2003, pp. 1566-1569. 

[2] Michael Vetter et al, High efficiency very large thin film silicon photovoltaic modules (HELATHIS), in: The 25th Europ. PVSEC (5th 

WCPEC) 6.-10. Sept. 2010, Valencia, Spain, pp. 3220 – 3223. 

85

86 

Nanophotonics 

Quantum Dot Based Thin Film Silicon Solar cells 

Akshatha Mohan, a.mohan@uu.nl, phone: 030 - 253 31 59 

Sponsor: FOM, since August 2010 

Supervisors: Prof. dr. R.E.I. Schropp and dr. Jatin K.Rath 

VHF PECVD, LBL, mass spectrometry, AFM, TEM 

Enhancing the performance of thin film silicon solar cells by using a wider spectral range of the 

solar spectrum is the aim of this project, which we intend to achieve by means of nanodot silicon 

(Si) based multijunction solar cells. Si and silicon-germanium (SiGe) nanodots are the materials of 

interest. The nanodots are made in a plasma enhanced chemical vapor deposition (PECVD) process 

by two methods namely (1) through gas phase creation of nanodots controlled by a pulsed plasma 

in a dusty regime and (2) layer by layer (LBL) growth process. One of the objectives will be to 

find which process has an advantage over the other as far as control of particle size, homogeneity 

of the particle sizes, doping efficiency of the impurities and control of the defects are concerned. 

Prior to growing the nanodots in the gas phase, the gas phase reactions and cluster formation was 

studied in the mass spectrometer, as these clusters are considered to be the precursors of the nanodots. 

Valuable information on the temperature and pressure dependence of polysilyl species was obtained. 

Si nanodots were also grown using LBL technique by alternating layers of SiH4 and H . We found 

2 

nanocrystals embedded in an amorphous matrix, whose structural properties were studied by AFM 

and top view TEM. 

By a judicious combination of nanodots produced in the two methods we will be constructing a 

tandem solar cell with the structure as shown in Fig 1. The theoretical efficiency of such a solar 

cell is 42.7%. 

Figure 1 : Schematic overview of proposed cell structure.

Atom-Light Interaction at the Nanoscale 

Björn Ole Mußmann, B.O.Mussmann@uu.nl, phone: 030 - 253 29 16 

Sponsor: NWO, since March 2010; FOM, since November 2010 

Supervisor: Dr. Dries van Oosten 

Nanofabrication, UHV, Laser Cooling, Spectroscopy 

Nanophotonics 

Figure 1: Graphical representation of the hole array and the trapped 

atoms. The vertical image on the left is a Scanning Near-field Optical 

Microscope (SNOM) measurement of the electric field of the light 

above the array. 

Extraordinary transmission through nano-hole arrays is a plasmonics related effect that aroused 

interdisciplinary interest in the past few years. It is exploited for chemical sensing, plays a role in 

the development of metamaterials and is a practical tool for fundamental research. It causes strongly 

localized, highly intense electromagnetic fields that are structured at a sub-wavelength scale. The 

very high energy density of these fields poses also excellent means to investigate non-linear optics. 

We will use this effect to trap rubidium atoms and to analyze the interaction between nano-hole 

arrays and the captured atoms. 

The nano-hole arrays are fabricated by Focused Ion Beam milling (FIB): A 90 nm thick film of 

gold is evaporated on a glass substrate. With a focused Gallium ion beam the desired structure is 

then milled into the gold film; in this case it is an array of square holes with diameters ranging 

from 50 nm to 600 nm. 

The structure is then inserted into a vacuum chamber. Clouds of rubidium atoms, precooled in a 

magneto-optical trap (MOT), are positioned in the proximity of the nano-hole arrays in the gold 

surface. Incident laser light is focused onto the structure. The extraordinary transmission through 

the hole array elicits a set of optical tweezers, capable of capturing the rubidium atoms very close 

to the gold surface. We will investigate the influence of the plasmons in the gold on the electron 

configuration of the rubidium atoms, as well as the change of plasmonic properties of the gold, 

evoked by the presence of these atoms. 

Figure 2: Colorized Scanning Electron 

Microscope (SEM) image of a nano-hole 

array. A 90 nm gold film on a glass 

substrate, with sub-wavelength pitch 

and hole-size. 

87

88 

Nanophotonics 

SnS Nanoparticles for CuInS 2 solar cells 

Caterina Prastani, c.prastani@uu.nl, phone: 030 - 253 31 59 

Sponsor: AgentschapNL, since November 2010 

Supervisors: Prof. dr. R.E.I. Schropp and dr. J.K.Rath 

TEM, HRTEM, PDS, Optical spectrometer, EDX 

Quantum dots (QD) can contribute to the enhancement of the efficiency of solar cells [1]. In 

particular, IV-VI semiconductor nanoparticles have received great interest, mainly because they can 

readily be synthesized. In this compound system, however, non-toxic nanomaterials are preferred 

for consumer products. 

Therefore, we have developed a new colloidal synthesis route of SnS nanoparticles, which are ideal 

for use in CIS type solar cells. SnS QDs are expected to enhance the efficiency of CIS solar cells, 

by creating intermediate band (IB) of the photoactive layers. Exploiting this concept it is possible 

to absorb more photons with sub-bandgap energy (Fig. 1). Transmission Electron Microscopy 

showed that the obtained SnS nanoparticles have a spherical shape (Fig. 2) with size less than 5 

nm, less than the Bohr radius, and a size distribution < 1.5%. By High Resolution Transmission 

Electron Microscopy (HRTEM) and Energy-Dispersive X-ray spectroscopy (EDX) the structure 

has been investigated. Nanoparticles are crystalline with orthorhombic structure and their chemical 

composition indeed is SnS (not SnS ). The optical characterization has been carried out using a 

2 

UV-VIS dual beam spectrometer and photothermal deflection spectroscopy (PDS) for absorption 

spectrum. The absorption spectrum is a continuum in the visible range and contains distinct peaks 

in the infrared region. 

Figure 1: IBSC CIS solar cell with SnS Figure 2: TEM image of SnS QDs. 

nanoparticles as intermediate layer 

and its energy band structure. 

[1] A.Luque, A. Martì and A.J. Nokiz, MRS Bullettin, 32 236 (2007). 

20 nm

Nanophotonics 

Impermeable Thin Film Encapsulation for Lighting, Displays and Solar cells 

on Foil 

Diederick Spee, D.A.Spee@uu.nl, phone: 030 - 253 32 63 

Sponsor: STW Perspectief Programma Thin Film Nanomanufacturing, since July 2009 

Supervisors: Prof. dr. R.E.I. Schropp and dr. J.K.Rath 

iCVD, Hot wire CVD, GPC, IR spectroscopy 

Thin film water and oxygen barrier layers will facilitate a large variety of sensitive electronic devices, 

such as solar cells on foil, OLEDs and rollable displays. A combination of SiNx and polymer layers, 

in our case poly-glycidyl-methacrylate (PGMA), is very suitable for this. SiNx layers are very 

impermeable to water and oxygen, however beyond a certain thickness the barrier properties do 

not improve any further due to defects (pinholes) propagating through the layers. By stacking these 

layers with polymer layers in alternating order, the chance of pinholes in different SiNx layers on 

exactly the same spot will be very small and an impermeable layer is created. 

The innovation that we bring to this field is that both polymer and inorganic materials can be 

deposited in a continuous process: SiNx using hot wire chemical vapor deposition (HWCVD) 

and PGMA using initiated chemical vapor deposition (iCVD), where an initiator is activated at a 

hot filament and starts the polymerization process. Since in both techniques no energetic ions are 

present, these barrier layers can even be deposited on delicate organic layers. Our research on the 

one hand concentrates on depositing stable PGMA layers to enable the deposition of SiNx on top 

of it. The stability is expected to increase with increasing average chain length of the polymer and 

a decreasing amount of defects in the polymer layer. On the other hand our goal is to lower the 

process temperature for the SiNx and the amount of highly reactive atomic hydrogen during the 

SiNx deposition process. Recent results show that the water vapor transmission rate of a 3-layer stack 

is less than 105 g/m2 .day, suitable for even the most sensitive OLED devices. A patent application 

has been submitted. 

Figure 1: Schematic picture of the utilization of multilayer barrier layers. 

89

90 

Nanophotonics 

Nanocrystalline silicon at high deposition rate for multi-junction solar cells 

Pim Veldhuizen, L.W.Veldhuizen@uu.nl, phone: 030 - 253 31 59 

Sponsor: NanoNextNL 


VHF PECVD, HWCVD, TEM, FTPS 

Nanocrystalline silicon (nc Si:H) is a highly absorbing, low band-gap semiconductor that can be used 

in thin film tandem solar cells. In order to increase the throughput and power output of a thin film 

silicon tandem solar cell production line, the deposition rate of nc Si:H needs to be increased beyond 

the presently industrially used deposition rate of ~2 Å/s. The challenge of this research is to enable 

the deposition of nc Si:H at high rate using very high frequency plasma-enhanced chemical vapor 

deposition (VHF PECVD) and hot wire chemical vapor deposition (HWCVD) while minimizing 

the negative effects that the high deposition rate can have on the material quality and uniformity. 

In this research particularly the effects of nc Si:H deposited at high rate on randomly or periodically 

textured surfaces on the nano scale that increase the path length of light in solar cells are investigated. 

Previous work showed that crystal growth of nc Si:H on steep textures gives rise to grain boundary 

formation and cracks [1] due to the collision of columnar growth, compromising the solar cell’s 

performance [2]. This research aims to mitigate this effect as well as other effects that decrease 

the quality of nc Si:H layers deposited at high rate by introducing incubation layers and profiling 

methods and by optimizing deposition techniques and surface textures. 

Figure 1: Cross sectional Transmission Electron Microscopy image of a nc-Si:H n-i-p solar cell deposited on a rough Ag/ 

ZnO coating. The white arrows point to the cavities and cracks, which appear not to be completely filled with silicon [1]. 

[1] R.E.I. Schropp, J.K. Rath, H. Li, Growth mechanism of nanocrystalline silicon at the phase transition and its application in thin film 

solar cells, Journal of Crystal Growth 311 (2009) 760. 

[2] H. Yamamoto, M. Isomura, M. Kondo and A. Matsuda: Proc. 11th PVSEC (PVSEC, Hokkaido, 1999) p. 231.

An elegant enhancement scheme for thin-film solar cells 

Jessica de Wild, j.dewild@uu.nl, phone: 030 - 253 25 09 

Sponsor: NL en UU F&M, 8 September 2008 

Nanophotonics 

Supervisors: Prof. dr. Ruud Schropp, dr. Jatin Rath, Prof. dr. Andries Meijerink, dr. Wilfried van Sark 

Spectral response, solar simulator, luminescence spectroscopy, time resolved laser spectroscopy 

This project aims at using photon upconversion to enhance the efficiency of existing thin film solar 

cells to bring an increase in efficiency by increasing the light absorption in the active semiconductor 

layer in the device [1]. Conventional p i n thin film amorphous silicon solar cells, which have a 

relatively high band gap (~800 nm), suffer from NIR photon losses due to the transparency of silicon 

for wavelengths higher than the band gap. By adding an upconversion layer and a highly reflective 

coating at the back surface of the solar cells these NIR photons can be converted to photons of 

visible wavelengths that can be absorbed by the solar cell and thus lead to extra photogenerated 

charge carriers. Further improvement will be achieved by improving the photon absorption in the 

upconverter layer and by making the back reflector diffusely reflecting so that it scatters the light 

into the cell more efficiently. 

We have proven this concept for the first time for amorphous silicon solar cells [2, 3], using 

an upconverter based on lanthanide ions. Lanthanides have the advantage that the electronic 

transitions are host independent but have the disadvantage that the efficiency is low due to the 

forbidden transitions. However, the efficiencies can differ drastically for different materials and more 

fundamental research on the mechanisms behind upconversion is done. 

The project is a collaboration between the Section Condensed Matter and Interfaces where the 

upconversion material is prepared and analyzed and the Section Nanophotonics, where the novel 

solar cells are optimized and characterized. 

Figure 1: Schematic illustration of the part of the solar spectrum that is transmitted (red) and the part that can be converted 

(around 980 nm) by NaYF up-converter (black) doped with Er and Yb as sensitizer. 

4 

[1] J. de Wild, A. Meijerink, W.G.J.H.M. van Sark, J.K. Rath, R.E.I. Schropp, Energy Environ. Sci., 2011, 4, 4835-4848. 

[2] J. de Wild, A. Meijerink, W.G.J.H.M. van Sark, J.K. Rath, R.E.I. Schropp, Towards upconversion for amorphous silicon solar cells, 

2010 SEMSC, p 1919, Vol 11. 

[3] J. de Wild, A. Meijerink, W.G.J.H.M. van Sark, J.K. Rath, R.E.I. Schropp, Enhanced near-infrared response of a-Si:H solar cells with 

β-NaYF4:Yb3+ (18%), Er3+ (2%) upconversion phosphors, 2010 SEMSC, p2395, Vol 12. 

91

92 

Nanophotonics 

Saturation effects in femtosecond laser ablation of silicon-on-insulator 

Hao Zhang, H.Zhang1@uu.nl, phone: 030 - 253 22 06 

Sponsor: CSC-UU, since OCT. 2009 

Supervisor: Prof. dr. Jaap Dijkhuis 

Femtosecond laser ablation, AFM, Optical microscopy, SEM 

Ultrashort pulse lasers have proven to be efficient for precise micromachining of metals, semiconductors 

and dielectric materials. Due to the nature of ultra short pulse duration, laser energy is 

delivered in a time shorter than electron-phonon relaxation time. This advantage over pico/nano 

pulse lasers makes precise material removal possible. However, due to the extreme pulse intensity 

(~1012 W/cm2 ) involved in a typical ablation process, laser-material interactions are highly nonlinear, 

even the first excitation stage is not fully understood. 

In a typical ablation experiment on silicon, a dense electron-hole plasma on the order of 1022 /cm3 and a few 104K is created. In such dense plasma, the laser penetration depth decreases by a factor 

of ~100 during the pulse itself. The attenuation in the plasma increases dramatically as the incident 

pulse fluence increases. As a result, there is a certain depth where the pulse fluence in that depth 

barely increases even if the incident pulse fluence increases. This means that, a saturation of ablation 

depth will occur in a certain range of pulse fluences. Fig. 1(a) shows this saturation effect observed 

in the experiment and the calculation by a model considering this extra absorption[1]. This regime 

is very interesting for both application and the study of laser absorption in such dense plasma. 

Technically, it is very beneficial for laser milling of layered structures such as silicon-on-insulator 

(SOI) because the ablation depth is insensitive to laser energy fluctuations. Experimentally, by 

measuring the ablation depth in this regime, one is actually measuring the laser fluence as a function 

of depth, which contains the information about the absorption process. Further investigation in 

this direction is on the way. 

Another topic of investigation is the effect of polarization on ablation. Radially polarized beams 

(Fig.1.b) can be focused into the smallest spot size possible by using far-field techniques due to 

the rotational symmetric polarization property[2]. The focused spot size is only limited by scalar 

diffraction theory. The use of this type of polarization in ultra-short laser ablation will be studied. 

Figure 1: Saturation effects in ablation of SOI: experimental data and calculation. (left); Experimentally generated radially 

polarized beam (right). 

[1] Hao Zhang, D. Van Oosten, D. M. Krol and J. I. Dijkhuis. Appl. Phys. Lett. 99, 231108 (2011). 

[2] R. Dorn, S. Quabis, and G. Leuchs. Phys.Rev.Lett. 91, 233901 (2003).

Nanophotonics 


Organic Chemistry and Catalysis 

93

94 


Development of Semi-synthetic Metalloenzymes for Olefin Metathesis 

Manuel Basauri Molina, M.BasauriMolina@uu.nl 

Sponsor: NRSC-C, since March 2010 

Supervisor: Prof. dr. Robertus J. M. Klein Gebbink 

Organometallic synthesis, NMR, ESI (MS), Homogeneous catalysis 

The cross-coupling of olefinic building blocks to form larger organic compounds, namely, olefin 

metathesis, is a powerful and widely used chemical technique that requires organometallic catalysts 

based on, for example, Ruthenium, i.e. Grubbs catalysts. The wide scope of olefinic substrates often 

results in a poor selective method generating a distribution of undesired side-products. A recent 

approach for the enhancement of selectivity without hampering the activity of these catalysts is to 

accommodate the latter in sterically hindered and chiral environments such as proteins, forming 

semi-synthetic enzymes, also called artificial metalloenzymes [1,2]. Efficient peptidic environments 

are still under investigation to properly confer the desired (enantio)selectivity in the active site. In 

the present project we synthesize Grubbs-like olefin metathesis catalysts bearing N-heterocyclic 

carbenes with a phosphonate esthers tail that allows for their covalent incorporation right in the 

active site of serine hydrolases (Figure 1, Linker a), an enzyme modification protocol developed by 

us where organometallic precatalysts are covalently and irreversibly incorporated in this large class 

of enzymes [3,4]; expecting that the proximity of the metallic center with the formerly working 

enantioselective environment will produce the so called 2nd coordination sphere needed to promote 

the selectivity in these hybrids. Other protein covalent modification strategies addressing nucleophilic 

aminoacids of different proteins are simultaneously been studied using haloacetamide and maleimide 

functionalities as linkers (Figure 1, Linkers b and c, respectively). 

Figure 1: A semi-synthetic metalloenzyme for selective olefin metathesis. 

[1] C. Lo, M.R. Ringenberg, D. Gnandt, Y. Wilson and T.R. Ward, Chem. Commun. 2011 (47) 12065; 

[2] C. Mayer, D.G. Gillingham, T.R. Ward and D. Hilvert, Chem. Commun. 2011 (47) 12068. 

[3] C.A. Kruithof, M.A. Casado, G. Guillena, M.R. Egmond, A. van der Kerk-van Hoof, A.J.R. Heck, R.J.M. Klein Gebbink and G. van 

Koten, Chem. Eur. J. 2005 (11) 6869; 

[4] B. Wieczorek, B. Lemcke, H.P. Dijkstra, M.R. Egmond, R.J.M. Klein Gebbink and G. van Koten, Eur. J. Inorg. Chem. 2010, 1929.


New Insight into C-Sn Bond Oxidative Addition on Palladium and Platinum 

Dr. Eric J. Derrah, E.J.Derrah@uu.nl, phone: 06 - 1372 92 55 

Sponsor: Arkema, since Sept 2011 

Supervisors: Prof. dr. Robertus Klein Gebbink and Prof. dr. Berth-Jan Deelman 

Organometallic synthesis, NMR spectroscopy, X-ray crystallography, ESI-MS 

Arkema is interested in the application of transition metal complexes as catalysts for the preparation 

of monoalkyltin species that are used to make SnO coatings on glass or as PVC stabilizers. 

2 

Understanding the mechanism of carbon-tin bond activation and formation at a transition metal 

centre is essential, as this could lead to the development of novel and improved processes for the 

production of monoalkyltin compounds. 

Previously it was found that the addition of methyltin trichloride to Pt(L) (PPh Py: Py = pyridyl) 

3 2 

resulted in the formation P–Sn–P pincer complex 1a by C–Sn bond oxidative addition (Scheme 1) 

[1,2]. Such species are potential intermediates in catalytic Sn-C bond forming reactions. Conversely, 

an experiment was performed where SnCl was added to platinum complex ([PtCl(Me)(L) ]) 

2 2 

containing a methyl group at Pt, indicating that the preferential isomer is the one also containing 

the Me moiety on the transition metal (1a), not the tin centre (2a). Full characterization of the 

related palladium derivatives was hindered due to the broad nature of the signals in the 1H, 13C and 119Sn NMR spectra, and poor solubility, which prevented the formation of crystals suitable 

for X-ray diffraction. Therefore, it was assumed that C–Sn bond activation also produces a Pd-Me 

species similar to 1a. 

A recent X-ray diffraction study of a related complex, prepared by the addition of n-butyltin 

trichloride to Pd(L) (PPh Im: Im = methylimidazole), shows that this initial assumption may not be 

3 2 

correct. In the resulting solid state structure the butyl moiety is clearly on the tin centre. A similar 

study for MeSnCl3 resulted in complex 2a confirming that the methyl group is on the tin centre. 

Unfortunately, poor solubility continues to hamper the structural characterization of all palladium 

complexes. In an effort to allow for a full characterization of these species, we have begun to prepare 

derivatives containing phosphine ligands with ‘solubilizing’ groups. Once these complexes have been 

formed the position of the alkyl group will be assigned by standard spectroscopic techniques, such 

as, ambient or variable temperature 1H, 13C, 119Sn, and 1H–NOSY NMR spectroscopy. 

When these species are fully characterized, the interconversion of 1 and 2 and their possible 

involvement in catalytic Sn-C bond formation reactions will be studied. 

Scheme 1: Two methods for the formation of P–Sn–P pincer complexes 1a-b or 2a-b. 

[1] Y. Cabon, H. Kleijn, M. A. Siegler, A. L. Spek, R. J. M. Klein Gebbink, B.-J. Deelman, Dalton Trans., 2010, 39, 2423 

[2] Y. Cabon, I. Reboule, M. Lutz, R. J. M. Klein Gebbink, B.-J. Deelman, Organometallics, 2010, 29, 5904. 

95

96 


Mononuclear Non-Heme Iron Catalysts for Cis-Dihydroxylation of Olefins 

Emma Folkertsma, E.Folkertsma@uu.nl, phone: 06 - 19002520 

Sponsor: NRSC-Catalysis, since September 2011 

Supervisor: Prof. dr. Robertus J.M. Klein Gebbink 

Organometallic synthesis, IR spectroscopy, ESI-MS, Homogeneous catalysis 

In nature heme-containing and non-heme iron 

enzymes are found to catalyze a broad array of dioxygen 

activating reactions, metabolic transformations, 

and C-H activation reactions. For decades, studies 

are performed on these enzymes as well as their 

synthetic analogues. Many mono-nuclear non-heme 

enzymes are found to share an active site in which 

two histidines and one carboxylato group occupy one 

face of the iron coordination sphere, called the 2-His- Figure 1: Active site containing 2-His-1-carboxylate 

1-carboxylate facial triad (Figure 1).[1] Furthermore, facial triad. 

the active catalytic species of these enzymes is found to be the high-valent iron-oxo state of the 

enzymes.[2] 

The aim of this project is to design a homogeneous mononuclear non-heme iron catalyst, selective in 

the cis-dihydroxylation of olefins by mimicking non-heme iron enzymes. The 2-His-1-carboxylate 

facial triad is mimicked in the N,N,O-ligands shown in the right side of Figure 2. These types of 

ligands often tend to form coordinately saturated complexes with two of these ligands coordinating 

to iron, leaving no open coordination sites for an oxygen donor and the substrate. Designing ligands, 

which bind only to one site of the iron center, is one of the major challenges of this project. Very 

bulky ligands will be designed as well as ligands with varying electronic properties. Furthermore, 

the influence of different co-ligands (L-L in left side of Figure 2) will be investigated. 

Figure 2: Left: Model for a N,N,O-iron complex bearing a bidentate coligand. Right: two N,N,O-ligands designed for this 

type of catalysts. 

[1] Bruijnincx, P. C. A.; van Koten, G.; Klein Gebbink, R. J. M. Chem. Soc. Rev. 2008, 37, 2716-2744. 

[2] Costas, M.; Mehn, M. P.; Jensen, M. P.; Que Jr, L. Chem. Rev. 2004, 104, 939-986.


Biomimetic catalysts on dendrimer: the next step toward application 

Dr. David Gatineau, D.M.R.A.Gatineau@uu.nl, phone: 06 - 48607268 

Sponsor: Marie Curie ITN “NANO-HOST”, since October 2011 


i- Organic and organometallic synthesis, NMR spectroscopy, chiral HPLC 

The development and application of environmentally friendly chemical processes is the main challenge 

in modern chemistry. In this respect, homogenous metal-catalyzed reactions have demonstrated 

very good efficiency and selectivity in the synthesis of natural and unnatural compounds. Iron has 

appeared as an attractive alternative to the use of toxic and expensive transition metals given its 

high natural abundance, low cost, and environmentally benign character. Furthermore, iron catalysts 

have recently shown promising results in selective oxidation reaction with hydrogen peroxide as a 

green oxidant (figure 1).[1] 

In spite of this great promise, the study of iron-catalyzed oxidation reactions remains challenging 

due to their low efficiencies. The recycling of the catalyst will allow for improvement of their 

efficiency and new perspectives for future large-scale application will be possible. In this context, 

our aim is to develop environmentally friendly and selective oxidation reactions of alkanes and 

alkynes catalyzed by iron complexes supported on dendrimers (figure 1). The immobilization of 

catalyst on dendrimers will not only ensure the selectivity of the monomeric catalyst due to the 

high solubility of these macromolecules but the recycling and reusing of the catalyst will be also 

realized by size-discrimination techniques to improve the efficiency of the catalyst.[2] 

Figure 1: Structure and reactions catalyzed by [Fe II (BPBP)] 2+ (left) and representation of [Fe II (BPBP)(X) 2 ] dendrimer (right). 

[1] a) Chen, M.S. and White, C., Sciences 318 (2007) 783. b) Suzuki, K., Oldenburg, L.P. and Que Jr, L., Angew. Chem., Int. Ed. 47 (2008) 

1887. 

[2] Yazerski, V.A., Klein Gebbink, R.J.M., “Heterogenization of Homogeneous Catalysts on Dendrimers”. In “Heterogenized Homogeneous 

Catalysts for Fine Chemicals Production”, Barbaro, P. and Liguori, F. (Eds.), Catalysis by Metal Complexes Series, Springer, London, 

United Kingdom (2010) 171. 

97

98 


Iron Catalyzed Direct Arylation of Unactivated Arenes with Aryl-Halides 

Yuxing Huang, Y.Huang@uu.nl, phone: 030 - 253 31 20 

Sponsor: China Scholarship Council, since October 2010 


Organic synthesis, ESI-MS, GC-MS, NMR 

Biaryl compounds are ubiquitous in pharmaceuticals and functional materials. Hence, they 

have received much attention from the pharmaceutical industry [1] as well as in materials and 

supramolecular science [2]. The most investigated way to construct biaryl compounds through 

metal mediated strategies mainly involves Ar1M as nucleophile and Ar2X as electrophile (M= Mg, 

B, Zn, etc.; X=Halides, etc.), e.g. in the Suzki-Miyaura cross-coupling reaction. 

Recently, direct arylation by means of C-H bond activation has been reported [3], in these cases 

the Ar1M coupling partner is replaced by Ar1H to react with Ar2X. This kind of strategy provides 

a much cleaner way to do cross coupling chemistry, which efficiently avoids the stoichiometric 

amount of metal waste from Ar2M. However, most reports are using expensive “noble” metals such 

as Pd. Therefore, using catalysts based on first row transition metals such as iron in direct arylation 

reactions may provide improved options for sustainable synthetic chemistry, due to their inexpensive 

as well as non-toxic and environmentally benign properties. 

At the moment our research focuses on the use of air stable and preformed iron (III) complexes as 

catalysts in direct arylation reactions involving C-H activation and their applications under ambient 

conditions and in technical solvents. 

Figure 1: Schematic picture of iron catalyzed direct arylation. 

[1] Hassan, J. Sevignon, M. Gozzi, C. Schulz, E. and Lemaire, M. Chem. Rev. 102 (2002) 1359. 

[2] Lehn, J. M. Science 295 (2002) 2400. 

[3] Alberico, D. Scott, M. E. Lautens, M. Chem. Rev. 107 (2007) 174.

Dehydration of alcohols to olefins by rhenium complexes 

Ties Korstanje, T.J.Korstanje@uu.nl 


Supervisors: Prof. dr. Robertus J.M. Klein Gebbink, dr. Johann T.B.H. Jastrzebski 


Catalytic testing, Gas chromatography (GC), Density functional theory (DFT), Organometallic synthesis 

In a world where oil is becoming scarce and therefore more expensive, the need for alternative 

building blocks for chemical industry is becoming more and more urgent. An important source 

for these building blocks is lignocellulosic biomass [1]. From this, building blocks such as glucose, 

3-hydroxypropionic acid and lactic acid can be obtained [2]. However, several challenges arise with 

the use of biomass as chemical building blocks, the most important being its high oxygen content. 

One of the ways to reduce this oxygen content is via controlled catalytic dehydration. 

We have developed a rhenium-based catalytic route for the dehydration of simple alcohols to olefins 

under mild conditions. First, we have investigated the reactivity of various rhenium compounds 

as catalyst for the dehydration of benzylic alcohols [3] and we have expanded this study to nonbenzylic 

alcohols such as allylic, aliphatic and homo-allylic alcohols. After these activity studies, we 

have applied the rhenium-based catalytic system to the dehydration of terpene alcohols, which are 

an important component of essential oils. Finally the rhenium-catalyzed upgrading of essential oils 

has been shown in a proof-of-concept experiment. 

[1] Ragauskas, A.J., Williams, C.K., Davison et al. , Science 311 (2006), 484. 

[2] Werpy, T. and Petersen, G. Top Value Added Chemicals From Biomass, Volume I, U.S. Department of Energy, 2004. 

[3] Korstanje, T.J., Jastrzebski, J.T.B.H., Klein Gebbink, R.J.M., ChemSusChem 3 (2010), 695. 

99

100 


Catalytic production of 1,3-butadiene from erythritol 

Suresh Raju, S.Raju@uu.nl, Phone: 06 - 26837541 

Sponsor: CatchBio, since October 2010 

Supervisors: Prof. dr. Robertus J. M. Klein Gebbink and dr. J.T.B.H. Jastrzebski 

NMR, GC, GC-MS, IR, ESI-MS, XRD 

Since fossil feed stocks are further depleting and increasing in price, it is essential to find an alternative 

source to produce energy, fuels and chemicals. Therefore renewable sources (biomass) are currently 

considered to be used as the feedstock towards the sustainable production of chemicals for the 

industries. After the pre-treatment of biomass, lignocellulosic biomass is obtained as the major 

component. This contains various polymeric compounds such as starch, cellulose and lignin. By 

breaking these polymers into smaller monomeric molecules, sugars, polyols and aromatic compounds 

are obtained. In particular the sugars and polyols contain many hydroxyl group functionalities and, 

accordingly, have a high oxygen content. In order to arrive at some of the main chemical building 

blocks, e.g. olefins, the challenge is to remove the hydroxyl groups. 

In principle, one can obtain the polyols by decarbonylation [1,2] of C and/or C sugars. Partial or 

5 6 

complete dehydroxylation of polyols then leads to the formation of olefins. The removal of hydroxyl 

groups can then be accomplished by means of dehydration [3] and deoxygenation [4] methods, or 

even deoxydehydration methods to arrive at olefins. Because rhenium has the tendency to attract 

and release oxygen atoms, rhenium oxo complexes have been considered for these types of reactions. 

Different ligated trioxo rhenium complexes have been reported in recent years for the conversion 

of polyols into their corresponding olefins [5]. Amongst those systems, we anticipate that the Cp*based 

catalyst [6] has the potential to be improved further through an optimization of electronic 

and steric ligand properties. Now we are working on the synthesis and catalytic performance of 

different substituted Cp-based trioxo rhenium complexes. 

Scheme 1: Deoxydehydration of 1-phenyl-1,2-ethanediol. 

[1] Sun J. and Liu H., Green chem. 13 (2011) 135. 

[2] Fabre L., Gallezot P. and Perrard A., J. of Catalysis 208 (2002) 247. 

[3] Korstanje T.J., Jastrzebski J.T.B.H. and Klein Gebbink R.J.M., ChemSusChem 3 (2010) 695. 

[4] Gable K. P. and Brown E., Organometallics 19 (2000) 944. 

[5] Ahmad I., Chapman G., and Nicholas K. M., Organometallics 30 (2011) 2810. 

[6] Cook G. K. and Andrews M. A., J. Am. Chem. Soc. 118 (1996) 9448.


Oxidative cleavage of olefins towards aldehydes and carboxylic acids 

Peter Spannring, P.Spannring@uu.nl, phone: 030 - 253 20 78 

Sponsor: Utrecht University, since mid-May 2009 

Supervisors: Prof. dr. Robertus J.M. Klein Gebbink, Prof. dr. B. M. Weckhuysen and dr. P.C.A. Bruijnincx 

ESI-MS, NMR, GC, FTIR 

Olefins can be found in nature as terpenes or unsaturated fatty acids, which are derived from 

vegetable oils and animal fats. Such alkenes can be oxidatively cleaved into mono-or dicarbonyls, 

i.e. aldehydes or carboxylic acids (Figure 1), which can be used in polymer, plasticizer, and stabilizer 

production. These products are also useful as intermediate building blocks for subsequent reactions. 

Expensive and often toxic transition-metal complexes derived from Ru,[1] W,[2] or Os[3] are known 

to catalyze these specific oxidative cleavages, with the help of reactive and relatively hazardous 

oxidants like NaIO or ozone. First-row transition-metal complexes are only known to cleave very 

4 

activated substrates like styrene-derivatives.[4] Permanganate may also be used for these reactions, 

yet it has to be used in stoichiometric amounts. 

Here, we present a study towards the use of more benign methods to oxidatively cleave internal 

double bonds. Ultimately, such procedures can be seen as green alternatives for the production of 

chemical building blocks from renewable vegetable oils and animal fats. 

Figure 1: General reaction equation of the oxidative cleavage of an alkene towards aldehydes and carboxylic acids. 

[1] Rup, S., Zimmermann, F., Meux, E., Schneider, M., Sindt, M. and Oget, N., Ultras. Sonoch. 16 (2009) 266. 

[2] Turnwald, S.E., Lorier, M.A., Wright, L.J. and Mucalo, M.R, J. Mat. Sci. Lett. 17 (1998) 1305. 

[3] Ley, S.V., Ramarao, C., Lee, A.L., Oostergaard, N., Smith, S.C., Shirley, I.M., Org. Lett. 5 (2003) 185 

[4] Dhakshinamoorthy, A., Pitchumani, K., Tetrah. 62 (2006) 9911 

101

102 


Immobilization of Homogeneous Catalysts on Dendrimers 

Vital A. Yazerski, V.Yazerski@uu.nl, phone: 06 - 57187238 

Sponsor: Marie Curie ITN “NANO-HOST”, since January 2009 


Organic synthesis, homogeneous catalysis, NMR, GC 

A major hurdle to implement molecularly defined catalysts, or homogeneous catalysts, in large-scale 

operations originates from the soluble nature of these catalysts and in particular is related to catalyst 

separation and reuse. Dendrimers are highly symmetrical, hyper-branched organic macromolecules 

and seem ideal supports of choice to arrive at soluble, yet supported homogeneous catalysts [1]. 

Dendrimer-supported homogeneous catalysts can be effectively separated from reaction media 

by means of nanofiltration for further use [2]. In this way the typical recycling properties of 

heterogeneous catalysts can be combined with the activity and selectivity properties of molecular, 

homogeneous catalysts. 

We put our efforts towards the immobilization of famous catalysts for such challenging 

transformations as iron-mediated (asymmetric) hydrocarbon oxidation using H O as an oxidant 

2 2 

[3,4] and enantioselective hydrogenation of bulky ketones with chiral Ru-PNN complexes [5]. 

To date several corresponding Fe- and Ru-containing dendritic catalysts have been prepared 

and tested in catalysis (see Figure 1). Currently we investigate the recycling potential of these 

molecularly enlarged homogeneous catalysts. Prospective simple recovery and recyclability of these 

macromolecular catalysts make them more attractive for synthetic purposes. 

Figure 1: Chiral dendritic catalysts for asymmetric hydrocarbon hydroxylation (C1), olefin epoxidation (C2) and ketone 

hydrogenation (C3). 

[1] Yazerski, V.A.; Klein Gebbink, R.J.M. “Heterogenization of Homogeneous Catalysts on Dendrimers” in Catal. Met. Complexes 2010, 

33 171–201. 

[2] Berger, A.; Klein Gebbink, R.J.M. and van Koten, G. Top. Organomet. Chem. 2006, 20, 1-38. 

[3] Gelalcha, F.G.; Bitterlich, B.; Anilkumar, G.; Tse, M.K.; and Beller M. Angew. Chem. Int. Ed. 2007, 46, 7293 –7296. 

[4] Chen M.S. and White C.M. Science 2007, 318, 783-787. 

[5] Clarke M.L.; Belén Díaz-Valenzuela M. and Slawin, A.M.Z. Organometallics 2007, 26, 16–19.

Physical and Colloid Chemistry 



103

104 


Magnetic separation by functional nanocomposites via equilibrium Pickering 

emulsions 

Roel Baars, r.j.baars@uu.nl, phone: 030 - 253 59 90 

Sponsor: STW SMARTSeparations, since September 2011 

Supervisors: Prof. dr. A.P. Philipse and drs. B.W.M. Kuipers 

Colloidal synthesis, TEM, complex magnetic susceptibility spectroscopy 

Emulsions play a large role in food and cosmetic industries and are an important field of research 

as such. From a practical point of view, one disadvantage is their thermodynamic instability, i.e. 

they require a (large) energy input for their formation. Microemulsions are an exception to this, 

but they require (co-) surfactants. 

Recently, a system has been found where solid-stabilized (Pickering) emulsions form spontaneously 

without the need for surfactants [1] (see Image 1). Since then, there has been an ongoing interest 

in the flexibility and usability of this system [2]. 

These emulsions are of great practical interest because of their uniform droplet size distribution 

(roughly 50–200 nm), the possibility of a variety of stabilizing agents (e.g. magnetic particles, 

creating magnetically responsive emulsions) and the possibility to coat the emulsion droplets to 

create core-shell like particles (e.g. with PMMA [3]). 

In our project we aim to employ these kinds of emulsions to create functionalized composite 

nanoparticles that are magnetically responsive. We opt for the coating of emulsion droplets with an 

amorphous layer of silica. Using silane coupling agents like TPM, this silica layer can be functionalized 

so that it may capture specific compounds from a solution or dispersion (e.g. functionalization 

with thiol-groups may capture gold particles). In a later phase we will develop a continuous flow 

setup to efficiently separate the magnetic composite particles from solution. The separation can be 

monitored by measuring the magnetic susceptibility of the solution. 

Figure 1: Transmission electron microscopy image of polymerized emulsion droplets covered with magnetite nanoparticles. 

[1] S. Sacanna et al., Thermodynamically Stable Pickering Emulsions. Phys. Rev. Lett. 2007, 98, 13-16. 

[2] D.J. Kraft et al., Conditions for equilibrium solid-stabilized emulsions. J. Phys. Chem. B 2010, 114, 10347-56. 

[3] S. Sacanna, A.P. Philipse, A Generic Single-Step Synthesis of Monodisperse Core/Shell Colloids Based on Spontaneous Pickering 

Emulsification. Adv. Mater. 2007, 19, 3824–3826.

Chemically bound magnetic nanoparticles in hydrogels 

Susanne van Berkum, S.vanBerkum@uu.nl, phone: 030 - 253 59 90 

Sponsor: STW, since April 2010 

Supervisors: Dr. Ben H. Erné and Prof. dr. Albert P. Philipse 

AGM, TEM, FTIR 


Magnetic hydrogels that swell or shrink due to changes in their chemical environment are required 

for a new type of biosensor that detects chemical changes magnetically. Hydrogels are highly crosslinked 

networks of polymer strands that can absorb large amounts of water while still maintaining 

their shape and structure. Upon swelling of a hydrogel, nanoparticles may leak from the gel causing 

loss of functionality of the sensor. 

To prevent leaking of nanoparticles from a hydrogel, nanoparticles can be chemically bound to 

the hydrogel. This is possible by replacing surface molecules on the nanoparticles such that the 

nanoparticles are not only incorporated in the hydrogel, but also part of the hydrogel network. In 

this case, oleic acid ligands are exchanged with acrylic acid so that the particles are incorporated in 

the network structure through the double bound characteristic of acrylic acid. [1] 

Backscattering experiments show that acrylic acid coated nanoparticles participate in polymerization, 

while diffusion of charge stabilized nanoparticles is only slowed down when viscosity increases. 

Magnetic susceptibility measurements also show that CoFe O nanoparticles coated with acrylic 

2 4 

acid are unable to rotate when incorporated in the hydrogel. This confirms that the particles are 

bound to the hydrogel network. 

Figure 1: (left) charge stabilized particle that remains unbound in a hydrogel (right) sterically stabilized particle that 

participates in polymerization and is bound to the hydrogel network. 

[1] Vo et al. Surface modification of hydrophobic nanocrystals using short-chain carboxylic acids. J.Coll. Int. Sci. 337 2009 75–80. 

105

106 


Self-assembled cubicle membranes 

Sonja Castillo, S.I.R.Castillo@uu.nl, phone: 030 - 253 25 40 

Sponsor: STW-Hyflux, since October 2010 

Supervisors: Prof. dr. Albert P. Philipse and dr. Dominique M.E Thies-Weesie 

Colloidal synthesis, TEM, SEM, IR spectroscopy 

Water treatment and water desalination require membranes that are highly selective, allow for a 

high flux with a sufficient chemical and physical resistance. We aim to develop novel inorganic 

separation membranes by the self-assembly of nano-porous, hollow cubic colloids into a densely 

packed array on a substrate (figure 1). The hollow cubic colloids are prepared from template cubic 

hematite colloids coated with porous silica (figure 2) [1]. We achieved size and shape control over 

the template particles, which is the first step of the development of cubicle membranes. Presently, we 

focus on expanding the properties of the inorganic coating layer. We employ surface-protected silica 

etching to increase the porosity and we monitor the process of silica etching with IR spectroscopy 

[2]. IR measurements have revealed that the etching process is a two step process, i.a. governed by 

the amount of protecting ligands. In addition, we are investigating the synthesis of titania coated 

cubic colloids [3]. Titania is chemically and mechanically robust, which makes it an interesting 

material for separation membranes. 

Figure 1: Schematic image of a cubicle membrane formed by a layer of hollowcubic silica colloids on a substrate. The cubes 

could contain a functionalized substance S. 

Figure 2: Hollow cubic colloids with a silica shell. Scale bar is 1 µm. [1]. 

[1] L. Rossi et al. Cubic crystals from cubic colloids. Soft Matter, 7(9):4139-4142, 2011 

[2] Y. Hu et al. Control over the permeation of silica nanoshells by surface-protected etching with water. PCCP, 12(38):11836-11842, 2010 

[3] A.F. Demirörs et al. A general method to coat colloidal particles with titania. Langmuir, 26(12):9297-9303, 2010


Osmotic pressure of interacting and non-interacting magnetic colloids 

Dr. Rocio Costo, R.CostoCamara@uu.nl, phone: 030 - 253 39 81 

Sponsor: STW-Hyflux, since September 2011 

Supervisor: Prof. dr. Albert Philipse 

Colloidal synthesis, TEM, Analytical centrifugation, IR spectroscopy 

Cobalt nanoparticles have higher volume magnetization values than other magnetic materials as iron 

or iron oxide. This high magnetization opens up a new field of research and practical applications. 

Cobalt nanoparticles can be synthesized by thermal decomposition of cobalt carbonyl leading to 

very monodisperse nanoparticles (polidispersity

108 


Self-organization of ‘colloidal molecules’ 

Chris Evers, C.H.J.evers@uu.nl, phone: 030 - 253 23 90 

Sponsor: NWO, since November 2011 

Supervisor: Prof. dr. Willem Kegel 

Colloidal synthesis, DLS, Optical microscopy, TEM 

Recently a method was developed in our lab to produce colloidal particles with adjustable number 

of patches and angles between them. We explore these new particles as a model system for selforganization 

by making theses patches sticky. The idea is to be able to tune the “valence” of the 

colloids, where valence is defined broadly as the potential number of bonds formed with other 

colloids. Ultimately, site-specific interactions between individual particles are expected to give rise 

to materials with new optical or mechanical properties. Furthermore, they can be used as a model 

system to more fundamentally understand the influence of valence on stability and formation 

dynamics of for example virus capsid assembly. 

The colloidal molecules synthesis route [1,2] is modified to make the seed part sticky by chemical 

modification, see figure 1. DNA can for example be bounded to functional groups on polystyrene 

spheres. Once chemically modified seed particles are obtained, swelling, heating and DNA binding 

is thought to give rise to colloidal molecules with DNA covalently bounded to the patches, which 

number and configuration can be tuned, see figure 1. 

Hydrogen bonding between base pairs of complementary DNA strands will make these patches 

sticky, and by changing the temperature, the stickiness can be turned on and off due to the reversible 

nature of DNA interactions. By using appropriate temperature programs, true ground-state structures 

can be found, whereas systems can be frozen by temperature quenches. 

Figure 1: Synthesis route for colloidal molecules with a valence. Cross-linked polystyrene spheres with functional surface 

groups are swollen with a monomer, and upon increasing the temperature to 80 degrees, the polymer network relaxes, 

and the monomer phase separates forming a protrusion. The liquid protrusions fuse and are polymerized, thereafter DNA 

is covalently bounded to the seed parts, making these patches effectively sticky. 

[1] D.J. Kraft, W.S. Vlug, C.M. van Kats, A. van Blaaderen, A. Imhof and W.K. Kegel, “Self-assembly of colloids with liquid protrusions,” 

J. Am. Chem. Soc. 131 (2009), 1182. 

[2] D.J. Kraft, J. Groenewold, W.K. Kegel, “Colloidal molecules with well-controlled bond angles,” Soft Matter, 5 (2009), 3823.

Self-assembly of colloids at the oil-water interface 

Julius de Folter, J.W.J.deFolter@uu.nl, phone: 030 - 253 23 90 

Sponsor: NWO-CW/ECHO, since January 2009 

Supervisors: Prof. dr. Willem K. Kegel and Prof. dr. Albert P. Philipse 

Interfacial tension, contact angle, optical microscopy, LSCM 


Emulsions are dispersions of oil droplets in water, or vice versa, and are abundant in many food, 

home and personal care products. In Pickering emulsions kinetic stability is provided by solid 

particles that adsorb strongly at the oil-water interface: the adsorbed particles act as a mechanical 

barrier retarding droplet coalescence. However, it was found recently that mixtures of TPM 

silicone oil, water and nanoparticles spontaneously form thermodynamically stable emulsions with 

monodisperse droplet diameters in the range 30-200 nm, resembling micro-emulsions. We found 

that the general requirements for these emulsions to form are the presence of charged colloids (< 

~100 nm), amphiphilic ions and oils with an oil-water interfacial tension γow < 10 mN/m. Current 

investigations focus on the creation of a Pickering emulsion system with similar features, replacing 

reactive oils with conventional oils and (co)surfactants. 

In recent years, the assembly of anisotropic particles at fluid-fluid interfaces has gained interest due to 

their increased availability and long-range interactions arising from their non-trivial wetting behavior. 

We explore the interfacial attachment of colloidal particles with a cubic shape. For this purpose, we 

have synthesized uniform micron-sized cubic particles which are adsorbed at the interface of oilin-water 

emulsions (Figure 1). Both the packing as well as the orientation of the colloidal cubes 

at the interface are studied. Moreover, cubic particles self-organize at various fluid-fluid interfaces 

enabling the investigation of limited coalescence and the formation of free particulate films. 

Figure 1: Colloidal cubes self-assemble at the oil-water interface. 

109

110 


Investigation and Manipulation of Dislocations and Stacking Faults in Colloidal 

Crystals 

Jan Hilhorst, J.hilhorst@uu.nl, phone: 030 - 253 36 50 

Sponsor: UU, since November 2007 

Supervisors: Dr. Andrei V. Petukhov, Prof. dr. Henk N. W. Lekkerkerker 

Scanning transmission X-ray microscopy (STXM), confocal fluorescence microscopy, focused ion beam 

lithography 

Colloids are particles with a size roughly between 1 nm and 1 μm in size. Such particles are small 

enough to exhibit Brownian motion, like molecules and atoms, but move much slower and are 

directly observable using visible light. This makes them ideal for studying processes related to 

crystallization, such as nucleation and growth dynamics, as well as annealing and final crystal structure. 

Their size also makes them attractive building blocks for photonic materials. If the periodicity of a 

colloidal crystal is right and a large refractive index contrast exists between the particles and their 

surroundings, a photonic band gap opens up; a band of photon energies that cannot propagate in the 

crystal. Photonic crystals are under investigation for application in solar cells, low threshold lasing, 

optical communication and even optical computing, but all of these require highly perfect crystals. 

Colloidal self-assembly, however, results in crystals that are far from perfect. The occurrence of point, 

linear and planar defects is frequent and hard to control. By studying the properties of these defects 

and the mechanisms by which they grow, we hope to find ways to prevent their inclusion or to be 

able to control their positioning. Using confocal fluorescence microscopy and X-ray microscopy, we 

study defect linear and planar defects in detail, relating their presence to the overall crystal structure. 

Using the knowledge obtained in this way, we can prepare crystal growth templates to selectively 

introduce faults to influence the final crystal structure, as shown in figure 1 for a real crystal. 

Figure 1: Side view of a face-centered cubic colloidal crystal into which stacking faults have been grown at predetermined 

positions.

Tunable attraction directing glass formation and gel collapse 


Dr. Dzina Kleshchanok, D.Kleshchanok@uu.nl, phone: 030 - 253 25 40 

Sponsor: FOM, since April 2009 

Supervisor: Prof. dr. H.N.W. Lekkerkerker 

SAXS, rheology 

Our work is directed towards the rheological modification of suspensions of natural and synthetic 

platelet-like particles. The addition of commercially available silica nanospheres provides depletion 

attraction between the platelet-like particles, the range and depth of which can be tuned by the 

size and concentration of the silica nanospheres. We found that this tunable attraction can lead both 

to glass formation and gel collapse. 

We studied the attractive glass formation in mixed gibbsite platelet/ sphere suspensions[1]. The 

structure of the glass was investigated in detail on the basis of the microradian x-ray diffraction 

measurements. In contrast to previously studied platelet systems where spherical depletants induced 

a liquid-crystalline phase formation, we show when the system is not able to access the equilibrium 

phases and the arrested state is formed instead (Figure 1). The use of depletion offers us an effective 

control over the strength and the range of the attraction in the system providing a possibility to 

tune between the liquid—crystalline and the arrested state formation in platelet suspensions. As, 

to our knowledge, this is the first experimental study on the attractive glass formed by colloidal 

platelets. Additionally, our study opens an opportunity to experimentally model the arrested state 

formation in suspensions of natural clays. Their suspensions are known to form arrested states at 

very low concentrations, while the liquid-crystalline phases could be found only seldom. 

In addition to the above we studied the effect of silica nanospheres on the rheological properties 

of hectorite gels. We observed that the gels of pure hectorite at low salt concentration collapse on 

the addition of silica nanospheres. This seems to be analogous to the observations of the delayed 

sedimentations in weak gel suspensions of spherical colloids upon the addition of non-adsorbing 

polymer[2]. 

The two observations described above indicate the possibility to tune the appearance and 

disappearance of arrested states and their rheological properties by the addition of simple and 

cheap nanospheres. 

Figure 1: Schematic picture of the glass formation in platelet/ sphere systems. To the right is a 2D scattering pattern from 

the glass sample. 

[1] Kleshchanok, D.; Meijer, J. M.; Petukhov, A. V.; Portale, G.; Lekkerkerker, H. N. W. Soft Matter 2011, 7, 2832. 

[2] Poon, W. C. K.; Starrs, L.; Meeker, S. P.; Moussaid, A.; Evans, R. M. L.; Pusey, P. N.; Robins, M. M. Faraday Discussions 1999, 112, 

143-154. 

111

112 


Polarity of Charged Quantum Dots 

Rob Kortschot, R.J.Kortschot@uu.nl, phone: 030 - 253 5990 

Employed by: NWO–CW/ECHO, since September 2009 

Supervisor(s): Dr. Ben H. Erné and Prof. dr. Albert P. Philipse 

Dielectric spectroscopy, laser Doppler electrophoresis, electroacoustics 

Semiconductor nanocrystals are also called “quantum dots”, because of the quantum-size effects 

in their optical and electronic properties. They are of great interest for applications in, for instance, 

fluorescent labels for biomedical imaging: they can be tagged to target molecules and have the 

advantage of a good resistance against photobleaching. The properties of a quantum dot are greatly 

affected by its electrical dipole moment and net electric charge. An electric dipole moment implies 

the presence of a strong internal electric field, which affects the electronic states and the allowed 

optical transitions through the Stark effect. Moreover, a net electric charge causes the optical 

and electronic properties to be drastically different than for a neutral quantum dot, resulting in a 

significantly lower photoluminescence quantum efficiency. Nevertheless, great uncertainty remains 

about the magnitude of the dipole moment of quantum dots and how it is affected by a net charge. 

The electric dipole moment of quantum dots can be determined by frequency-dependent dielectric 

measurements (dielectric spectroscopy). Our existing differential magnetic susceptibility measurement 

setup was modified so that it can be used for dielectric spectroscopy. Our first measurements on 

liquids with low concentrations of nanoparticles demonstrate that the dielectric permittivity can 

be measured sensitively in the range from 100 Hz to 2 MHz, the typical range for thermal rotation 

of nanoparticles in a liquid. A transparent capacitor was developed to study the dipole moment 

both in the dark and under illumination. 

Additionally we are exploring the use of electroacoustics. This technique employs ultrasound, as a 

result of which the colloids move due to a density contrast between colloid and solvent, and the 

dynamic mobility is measured from the resulting colloid vibration current (CVI). The dynamic 

mobility of TPM-coated silica particles in ethanol were measured at different ionic strengths. At 

high ionic strengths the dynamic mobility (at 3.3 MHz) equals the electrophoretic mobility, which 

was measured with laser-Doppler electrophoresis. At low ionic strength, however, the dynamic 

mobility is significantly higher than the electrophoretic mobility, which can probably be attributed 

to Maxwell-Wagner relaxation of the double layer.


Preparation and application of colloidal metal pyrophosphate salts 

Mikal van Leeuwen, Y.M.vanleeuwen@uu.nl, phone: 030 - 253 39 81 

Sponsor: SenterNovem, since September 2009 

Supervisor: Prof.dr. W.K. Kegel and dr. K.P. Velikov 

Colloidal synthesis, DLS, SEM, TEM 

The pyrophosphate anion (diphosphate, P2O74- or PPi) is part of the biological energy cycle 

and DNA synthesis, released upon hydrolysis of adenosine triphosphate (ATP) to adenosine 

monophosphate (AMP): ATP → AMP + PPi. Insoluble salts of metal pyrophosphate are known 

for their wide industrial and biomedical applications[1]. Furthermore, as iron(III)pyrophosphate 

(FePPi) is one of the few white materials containing iron, it is commercially available as a food 

additive and mineral supplement. It is an easily concealable material and useful for fighting iron 

deficiency because of its good bioaccessibility[2]. While these applications can greatly benefit from 

a colloidal approach, the majority of current literature concerns the macroscopic crystals and bulk 

material. Moreover, control of the particle morphology is important for many of the biological 

and food applications since health risks can be induced by particle size and shape, asbestos being 

a notorious example. 

In collaboration with Unilever we study the preparation, characteristics and possible applications 

of colloidal metal pyrophosphate salts. In recent work we have shown for the first time a systematic 

study into the morphology and properties of several colloidal metal pyrophosphate salts depending 

on metal ion valence and nature. Our key finding is that trivalent metal ions always form amorphous 

materials with pyrophosphate, while divalent metal ions form crystalline particles, see Figure 1. The 

morphology of the crystalline particles can be further modified using colloidal synthesis techniques 

such as autoclave treatment or surfactant addition.[3] 

Figure 1: Representative TEM images of pyrophosphate prepared with (a) trivalent or (b-d) divalent metals. 

[1] E.g. U. Gbureck, T. Hölzel, L. M. Grover J. Mater. Sci.: Mater. Med. 2008, 19, 1559-1563, Belkouch, J. B. Taouk, G. Hecquet, Studies 

in Surface Science and Catalysis, 1994, 82, 819-828. 

[2] F. M. Hilty, M. B. Zimmermann, Nature Nanotechnology, 2010, 5, 374-380. 

[3] Y. M. van Leeuwen, K. P. Velikov and W. K. Kegel, RSC Advances, Accepted. 

113

114 


Structure Formation in Mineral Liquid Crystals in Confinement 

Anke Leferink op Reinink, A.B.G.M.LeferinkopReinink@uu.nl, phone: 030 - 253 25 40 

Sponsor: FOM, since November 2009 

Supervisors: Prof. dr. H.N.W. Lekkerkerker, dr. A.V. Petukhov and dr. G.J. Vroege 

SAXS, polarization microscopy, confocal fluorescence microscopy, TEM 

Anisotropic colloids are known for their ability to form liquid crystalline phases. In the bulk 

suspension platelike gibbsite particles can, depending on the polydispersity and volume fraction, 

form a nematic and a (hexagonal) columnar phase. The goal of this project is to investigate how 

structure formation is influenced by confinement. 

Gibbsite suspensions are therefore studied in wedge shaped cells. The role of confinement is 

increasing towards the tip of the wedge. The liquid crystal structures are studied with SAXS, but 

problems arise because of the small cell thickness. Therefore large platelets (D≈600 nm) are of 

interest because they are optically accessible with optical microscopy. Adapting the colloidal system 

for confocal fluorescence microscopy is work in progress. 

These large gibbsite platelets have shown to form hexagonal columnar phases. Due to their size 

they sediment faster, causing the columnar phase to be distorted. With SAXS this is observed as 

a vertical deformation of the pattern (fig. 1a). Figure 1b and c show that with increasing effect of 

confinement, this vertical distortion of the pattern has disappeared; the distortion is suppressed by 

confinement. It is also expected that confinement promotes better particle ordering. 

Particle self-organization in confinement can be further manipulated by external, for example 

magnetic and electric, fields. In an electric field the platelets align with their normals perpendicular 

to the field. SAXS and polarized light microscopy studies show that in an isotropic suspension a 

paranematic phase with a negative order parameter is formed within seconds when an electric field 

is applied. The paranematic ordering enhances with increasing field strength and strongly depends 

on frequency of the field. 

Future plans comprise patterning of the cell surfaces to anchor the platelets perpendicular to their 

natural behavior. 

A B C 

Figure 1: 2D scattering patterns of a dispersion of gibbsite platelets in a wedge cell (wedge angle of 0.05º) which was 

stored vertically, i.e. with the tip of the wedge at the bottom taken at a distance of a) 12mm b) 2.0mm and c) 0.5mm 

from the tip of the wedge.

Order and disorder in colloidal crystals 

Janne-Mieke Meijer, J.Meijer1@uu.nl, phone: 030 - 253 36 50 

Supervisors: Prof. dr. Henk Lekkerkerker and dr. Andrei Petukhov 

Confocal fluorescence microscopy, SAXS, Full Field HRTXM, SLS 


The formation of colloidal crystals has been of interest for many years as it serves as a model of 

crystallization on atomic scale. Differently shaped colloidal model systems are used, comprised 

of spheres or cubes, as particle shape and interactions are known to greatly influence the final 

crystal symmetry. The resulting crystalline structures are characterized with confocal fluorescence 

microscopy, Small Angle X-ray Scattering (SAXS) and novel full field High Resolution Transmission 

X-ray Microscopy (HRTXM). 

However, the formed crystalline structures are not ideal. Disorder is always present in different 

forms such as vacancies, (partial) dislocation and stacking disorder. As the properties of crystalline 

solids are determined by the presence of defects, it is important to understand their formation, 

diffusion and interaction. Using X-ray microscopy, the inner structure of the crystalline systems, 

even that of optically opaque crystals, is investigated in real and reciprocal space. In figure 1 on the 

left examples of the SAXS pattern of a crystal of silica spheres (top) and that of hematite cubes 

ordered in a magnetic field (bottom) show (long range) crystalline ordering. HRTXM images of 

the same position in the crystals obtained with hard x-ray microscopy, a technique which is still 

under development, are shown on the right. 

Figure 1: (left) SAXS pattern of crystalline sediment of silica spheres and slightly rounded hematite cubes (right) HRTXM 

images of the samples, showing interlayer and interparticle orientations. 

115

116 


Colloids with a valence: a model system to study self-organization 

Bas van Ravensteijn, b.g.p.vanravensteijn@uu.nl, phone: 030 - 253 36 50 

Sponsor: NWO, since November 2011 

Supervisor: Prof. dr. Willem Kegel 

TEM, SEM, NMR, FTIR 

The objective of the proposed research is to develop colloidal particles with adjustable valence, and 

study their aggregation properties. Here, ‘valence’ is defined broadly as a measure for the potential 

number of bonds formed with other colloids, and corresponds to the number of sticky patches on 

the surface of a colloidal particle. Recently, a method to produce colloidal particles with adjustable 

number of patches and angles between them was developed [1,2]. 

Figure 1: Schematic representation of preparation of patchy particles (left) and how fusion of these particles leads to the 

formation of colloids with multiple patches (right). 

We propose to exploit and explore this unique system by making the patches sticky by selective 

chemical modification which eventually leads to shape and chemical anisotropic colloids. As a starting 

point, colloidal particles decorated with epoxide moieties on their surfaces will be synthesized. These 

epoxide groups open the way to a wide variety of other functionalities accessible via (straightforward) 

organic chemistry, or to the direct coupling of more complicated chemical structures such as dyes 

(Figure 2). 

Figure 2: Chemical diversity of the epoxide group opens routes toward a variety of surface functionalities. 

We aim to develop a robust synthetic procedure towards these colloids in which one can systematically 

vary the desired surface functional groups, thereby opening routes towards highly sophisticated 

model systems for self-organization of shape and chemical anisotropic colloids. 

[1] D.J. Kraft, W.S. Vlug, C.M. van Kats, A. van Blaaderen, A. Imhof and W.K. Kegel, “Self-assembly of colloids with liquid protrusions,” 

J. Am. Chem. Soc. 131 (2009), 1182. 

[2] D.J. Kraft, J. Groenewold, W.K. Kegel, “Colloidal molecules with well-controlled bond angles,” Soft Matter, 5 (2009), 3823.

Interactions and properties of binary colloidal nanocrystal solids 

Jos van Rijssel, J.vanRijssel@uu.nl, phone: 030 - 253 23 90 

Sponsor: FOM-NPS 

Supervisors: Dr. Ben H. Erné, Prof. dr. Albert P. Philipse 


Cryogenic-Tomographic-TEM, Dynamic Light Scattering(DLS), Alternating gradient magnetometry(AGM), 

Laser-Doppler electrophoresis 

The main goal of this project is to understand the formation of binary superlattices of colloidal 

nanocrystals. These superlattices are new materials that combine the properties of individual 

nanocrystals, for instance the fluorescent properties of semiconductor quantum dots and the 

magnetic properties of ferromagnetic nanoparticles. 

In the formation of these superlattices many complex interactions are involved. We will measure the 

strength of these interactions by direct observation of the equilibrium structures of the nanoparticles 

in a liquid dispersion as visualized with cryo-TEM (figure 1) both in 2D and 3D. Not only 

information about the particle-particle interactions can be obtained but various properties related 

with the structure of nanoparticle dispersions can be accessed. Additional information about the 

nature of the interactions will be determined with other techniques, such as magnetometry and 

laser Doppler electrophoresis. 

Besides this we will also characterize the properties of these nanoparticle superlattices; for instance, 

we plan to make superlattices of semiconductor quantum dots and ferromagnetic nanoparticles and 

to study the resulting fluorescent and magnetic properties. 

Figure 1: Schematic representation of the interaction strength from cryo- TEM of particles in a liquid medium. Analysis of 

the images yields the positions of the particles from which the cluster size distribution is determined. From this distribution 

the pair interaction free energy can be calculated. 

117

118 


Cubic colloids and their applications 

Laura Rossi, L.Rossi@uu.nl, phone: 030 - 253 39 81 

Sponsor: Senter Novem, since June 2008 

Supervisors: Prof. dr. Albert P. Philipse and Prof. dr. Willem K. Kegel 

TEM, SEM, Optical microscopy, Confocal fluorescence microscopy 

A fundamental issue in condensed matter science is the relation between particle shape and the 

symmetry and structure of the crystals they form. The simplest (but rare) crystal structure in nature 

is cubic and its natural building block is the cube. We have prepared micron-sized silica hollow cubic 

colloids using hematite cubic particles as template. To induce the particles self-assembly we made 

use of the well-known depletion forces that arise when the colloids are dispersed in the presence 

of a non-adsorbing polymer. These attraction forces surprisingly arrange the particles in a registered 

configuration (Figure 1) yielding simple cubic crystals, a direct consequence of the shape of the 

cubes that have slightly rounded edges. 

In this project, we are currently busy investigating the effect of the polymer size on the crystal 

structure. 

The colloidal cubes presented in the figure below are also studied for their use as micro-capsules for 

the preparation of a variety of inorganic and organic colloids, which is very useful for the control 

of the particle shape, size and stability during synthesis. 

Application of the particles as delivery carriers for food nutraceuticals is also under investigation. 

Figure 1: Schematic picture of the self-assembly of micron size hollow colloidal cubes (imaged by TEM and SEM, left) to 

simple cubic crystals (imaged by optical –top-, and confocal –bottom- microscopy).

Water–water pickering emulsions 

Mark Vis, M.Vis@uu.nl, phone: 030 - 253 39 81 

Sponsor: NWO/CW (ECHO grant), since January 2012 

Supervisors: Dr. B.H. Erné, dr. R.H. Tromp, and Prof. dr. A.P. Philipse 


Optical microscopy, interfacial tension measurements, electrochemical potential measurements, electrical 

impedance spectroscopy 

Emulsions are of great practical importance for many everyday substances such as foods and 

pharmaceuticals. They often consist of oil droplets dispersed in water or vice versa. While normally 

a mixture of oil and water quickly undergoes phase separation into pure oil and water, emulsifiers 

and stabilizers can be used to stabilize the droplets, for instance by decreasing their surface tension 

and/or preventing their coalescence. 

It has been found that some aqueous polymer mixtures also undergo phase separation [1], as shown 

in Figure 1. In this example, an aqueous solution of gelatin is mixed with an aqueous solution 

of dextran. Two immiscible phases are formed, one rich in gelatin and the other rich in dextran. 

Interestingly, both phases consist for over 90% of water, to which the interface is permeable. 

By vigorously mixing such a system, a short-lived emulsion can be prepared, which rapidly undergoes 

coalescence to form again two macroscopic phases. To prepare more stable emulsions, emulsifiers or 

stabilizers are needed, which are presently unknown for these kinds of systems. It would however 

be of great commercial interest to be able to prepare sufficiently stable water–water emulsions, for 

instance as a way to texturize water without using oil or fat. 

The present fundamental research focuses on characterizing the interface between these two phases 

and exploring the possibilities to stabilize such emulsions by adsorbing colloidal particles at the 

interface, so-called Pickering emulsions. The study will include measurements of the ultra-low 

interfacial tension, of the electrical potential step across the interface, and of the capacitance of 

the interface. 

Figure 1: An aqueous mixture of gelatin and dextran separates into a gelatin-rich phase (α) and a dextran-rich phase (β), 

as shown by a photograph (top) and a phase diagram (bottom) [1]. The phase diagram does not depend on temperature, 

which indicates that the phase transition is entropy driven. 

[1] M.W. Edelman et al., Biomacromolecules 2, 1148–1154 (2001). 

119

120 


Self-organization of ‘colloidal surfactants’ 

Joost Wolters, J.R.Wolters@uu.nl, phone: 030 - 253 23 90 

Sponsor: NWO-CW, since January 2011 

Supervisors: Prof. dr. W. K. Kegel and dr. A. Petukhov 

Colloidal synthesis, Optical microscopy, TEM, DLS 

Colloids can be used as building blocks for larger structures. Simple, isotropic colloids can only 

form basic colloidal crystals, whilst colloids that exhibit anisotropic interactions can be designed 

to self-assemble into more complex structures. Recently a method was developed in our group to 

synthesize colloidal molecules with a variable number and orientation of patches with different 

surface properties [1]. By making these patches ‘sticky’, colloidal particles can be formed with a 

certain ‘valency’, i.e. able to make a certain number of bonds at a well-defined angle. 

In this project, interaction between particles is made anisotropic by creating variation in the surface 

roughness. When choosing the right depletant size, the overlap volume of two smooth surfaces is 

higher than that of two rough ones, making the smooth parts of the particle sticky. 

Particles with a single sticky protrusion can be regarded as colloidal surfactants, expected to form 

micelle-like structures. Variations in ratio between the rough and smooth side influences the 

structures formed. Particles with more attractive patches are expected to form more complex 

structures like chains, spirals or sheets. 

Figure 1: Optical microscopy images of structures formed by particles with one smooth (sticky) protrusion and a schematic 

representation (bottom right) of structures formed by particles with more than one sticky protrusion. 

[1] D.J. Kraft, W.S. Vlug, C.M.v. Kats, A.v. Blaaderen, A. Imhof, and W.K. Kegel, JACS 131 1182, (2009).

Soft Condensed Matter and Biophysics 



121

122 


The Integrated Laser and Electron Microscope: iLEM 

Dr. Alexandra Agronskaia, A.V.Agronskaia@uu.nl, phone: 030 - 253 28 25 

Sponsor: STW, since December 2004 

Supervisor: Prof. dr. H.C. Gerritsen 

Integrated correlative microscopy, scanning fluorescence microscope, Transmission Electron Microscope, 

sample preparation for iLEM 

Correlative microscopy, combined fluorescence and electron microscopy on the same specimen, 

has become increasingly popular over the past years. Electron microscopy (EM) is the technique of 

choice to study specifically labeled proteins inside the cellular matrix at high resolution. However, 

EM is limited in its capability of locating labeled proteins in large fields of view. Fluorescence 

microscopy (FM) can find specific labels in large fields of view but has limited resolution. Correlative 

light and electron microscopy (CLEM) combines the advantages of both techniques. We are using 

an integrated approach to CLEM: the iLEM (integrate laser and electron microscopy). The iLEM 

consists of a home-made laser scanning fluorescence microscope module mounted on a standard 

transmission electron microscope. The fluorescence microscope has 0.55 mm lateral resolution, 

500x500 μm2 field of view, 1 frame per second acquisition rate and the light and electron images 

can be correlated within


Depletion driven self assembly of anisotropic colloidal building blocks 

Dr. Douglas Ashton, D.J.Ashton@uu.nl, phone: 030 - 253 12 87 

Sponsor: Since August 2011 

Supervisor: Prof. dr. M. Dijkstra 

Monte Carlo simulations, Variable box-shape NPT simulations 

As synthesis techniques become evermore sophisticated the availability of colloidal particles of 

various different shapes and sizes has increased dramatically. From spheres and rods to multifaceted, 

or even concave particles, these new building blocks offer many exciting opportunities in 

the development of advanced new materials and devices. 

In order to achieve such goals it is important to understand, and precisely control, the interactions 

between the particles. A useful tool to this end is the addition of non-adsorbing polymers or 

nanoparticles to induce an attractive depletion force between the colloids. Depletion is a purely 

entropic effect, which can be easily tuned by altering the size and quantity of the depletant. 

Our aim is to understand the structure and phase behaviour of anisotropic colloid-polymer mixtures 

through computer simulation. Due to the large size-asymmetry of such systems specialised Monte 

Carlo techniques, such as the geometric cluster algorithm (GCA), are required. The GCA has been 

extended to operate in densely packed clusters such as those shown in Figure 1. In this particular 

case, as recently seen in experiment [1], rounded cubes can assemble into square arrays, stabilised 

by depletion. 

Figure 1: Simulation snapshot of colloidal cubes assembling on a substrate. 

[1] Rossi et. al., Soft Matter, 7, 4139-4142 (2011). 

123

124 


Liquid crystal phases of colloidal boardlike particles 

S. Belli, S.Belli@uu.nl, phone: 030 - 253 59 05 

Sponsor: FOM, since Oct 2009 

Supervisors: Prof. dr. Ir. Marjolein Dijkstra and dr. René van Roij 

Density Functional Theory, Monte Carlo and Molecular Dynamics simulations 

One of the most ambitious goals of material science is to understand and control the macroscopic 

properties of a body from the knowledge of the interactions between its particles. In this context 

liquid crystal phases, states of matter in which anisotropic interactions determine variable optical 

and rheological properties, are extremely interesting systems. Typical liquid crystal states, such as 

those used in electronic display technology, are characterized by optical uniaxiality. However, the 

aim of stabilizing biaxial (nematic) states, first predicted almost 40 years ago, is still an open problem 

with wide potential technological relevance. 

We focus on the stability of biaxial nematic liquid crystals developed by colloidal boardlike particles, 

i.e. “bricks”. By means of density functional theory, we show that polydispersity explains the 

unexpected biaxial nematic stability [1] observed in a recent experiment [2]. Moreover, we predict 

that the depletion attraction induced by a polymeric depletant can lead to analogous behavior [3]. 

Our predictions will be compared with numerical simulations [4]. 

Figure 1: Left: typical phase diagram of boardlike particles as a function of the size polydispersity of the system. Right: 

snapshot of a state of boardlike particles generated by Monte Carlo simulation. 

[1] S. Belli, A. Patti, M. Dijkstra and R. van Roij, Phys. Rev. Lett. 107, 148303 (2011). 

[2] E. van den Pol, A. V. Petukhov, D. M. E. Thies-Weesie, D. V. Byelov, and G. J. Vroege, Phys. Rev. Lett. 103, 258301 (2009). 

[3] S. Belli, M. Dijkstra and R. van Roij, arXiv 1111.4132 (2011). 

[4] S. Belli, F. Smallenburg, R. van Roij and M. Dijkstra, work in progress.

Self-assembly, drying and fracture of colloidal suspensions 

Thijs Besseling, T.H.Besseling@uu.nl, phone: 030 - 253 35 19 

Sponsor: FOM, M2i, since June 2010 

Supervisor: Prof. dr. Alfons van Blaaderen 


Confocal Fluorescence Microscopy, Particle Tracking, High Precision Parallel Plate Oscillating Shear Cell 

(HIPPOS) 

Drying of a colloidal suspension is a common phenomenon in nature and can give rise to interesting 

self-assembled patterns. During evaporation of the solvent pressure is exerted on the particles, which 

can lead to large stresses and undesirable fracture of the material. Indicative of the complicated 

nature of this problem is that there are several models that contradict each other on even the 

most basic assumptions and the situation gets even more complex when the goal is to end up 

with regular arrangements of particles. We want to significantly increase our understanding of this 

process both for colloidal crystalline as amorphous particle films using a new approach (quantitative, 

time and position resolved 3D real-space confocal analysis) together with model particle systems 

in which we can tune the size, shape, interactions (including the elastic constants of the particles 

and films), viscosity, wetting angle (particle and surface) and application method (‘shear’, ‘vertical 

and horizontal drying’). 

Recently, it was shown that the (in)famous ‘coffee-ring-effect’ is almost completely suppressed when 

a drying suspension consists of ellipsoids instead of spheres, due to a difference in deformation of 

the fluid-air interface [1]. Inspired by this example, we want to investigate the correlation between 

the drying behavior of non-spherical particles and structure formation, using a model system of 

fluorescent rod-like silica particles [2] and external fields such as electric fields and shear flow. With 

recently developed image analysis software we can determine that positions and orientations of the 

particles and subsequently quantify the structure with 3D bond (orientational) order parameters. 

Figure 1: Shear-induced columnar phase of fluorescent silica rods with length L = 3.3 μm and diameter D = 550 nm (L/D = 

6), dispersed in a water/dimethyl sulfoxide (DMSO) mixture. 

[1] Yunker, P. J., Still, T., Lohr, M. A, & Yodh, A. G. Nature 476(7360), 308-311 (2011). 

[2] Kuijk, A., van Blaaderen, A., & Imhof, A. JACS 133(8), 2346-2349 (2011). 

125

126 


Smart nanoparticles at the oil-water interface for enhanced oil recovery (EOR) 

Nina Elbers, N.A.Elbers@uu.nl, phone: 030 - 253 23 63 

Sponsor: FOM and Shell, since October 2010 


Confocal fluorescence microscopy, Optical microscopy, SLS, Conductivity measurements 

The aim of this research is to develop permeable shells that can act as ‘containers’ for certain 

chemicals. By manipulating the absorption and desorption behaviour of these shells, preferentially by 

a trigger, one could release the contents of the shells in a controlled and localized way. These systems 

are for instance interesting for drug delivery purposes and for surfactant flooding, an enhanced oil 

recovery (EOR) technique, in which surfactants are used to reduce the interfacial tension between 

oil and water still remaining in the rocks. By combining the triggered release of surfactants with, 

possibly, a strong adsorption of the shells to the oil-water interface, we hope to reduce the surface 

tension to such a level that spontaneous emulsification becomes possible. 

For a proof of principle, we start with the synthesis of monodisperse, micron-sized silica/siloxane 

shells using a method that was developed in our group [1]. Experiments have been performed to 

manipulate the shell-growth step and to improve control over the shell size and thickness. Previous 

experiments have already shown that the shells can be loaded with different functional oils like 

silicone oil, octamethylcyclotetrasiloxane and lower hydrocarbon oils. In preliminary experiments 

it is investigated whether these shells can also be loaded with surfactants for EOR purposes (Figure 

1). By labeling the shells with a fluorescent dye, the system can be monitored with Confocal Laser 

Scanning Microscopy (CLSM). Moreover, optical microscopy, Static Light Scattering (SLS) and 

conductivity measurements are used to monitor shell formation as well as the size and monodispersity 

of the system. 

Figure 1: Left) Confocal microscopy images of silica\siloxane shells (20 nm thickness) that buckle when the system is dried. 

Right) Preliminary experiments indicate that these dried shells unbuckle after addition of a fluorescently labeled liquid 

surfactant phase because of shell filling. 

[1] Carmen I. Zoldesi and Arnout Imhof, Adv. Mater. (2005), 17, 924-928.


Advanced spectroscopy based imaging for biological applications 

Dr. Farzad Fereidouni, F.fereidouni@uu.nl, phone: 030 - 253 28 23 

Sponsor: Utrecht University 

Supervisor: Prof. dr. Hans. C. Gerritsen 

Confocal fluorescence microscopy, microscopy/spectroscopy (STM/STS) 

Lifetime and spectral imaging can be used for imaging of metabolic processes and identification of 

biochemical compounds in tissue. Fluorescence lifetime imaging is a versatile tool and both time 

correlated single photon counting (TCSPC) and time gating methods have been used for probing 

the local environment of the fluorescent molecules or to discriminate different molecules and to 

detect molecular interactions at the nanometer scale. Besides lifetime imaging, spectral imaging is 

also utilized to study colocalization of multiple fluorophores or identifying (intrinsic) fluorophores. 

Demonstration of proximity of proteins to monitor the interaction in cells is of great importance 

in biological applications and developing a spectrally resolved fluorescence lifetime measurement 

method to study the Förster resonant energy transfer (FRET) is one of the main goals. 

[1] Lakowicz, J. R. (1999). Principles of Fluorescence Spectroscopy. Plenumpress, New York. 

[2] Pawley, J.B.(2006) .Handbook of Biological Confocal Microscopy. Springer, New York. 

127

128 


Phase Behavior of Faceted Hard Polyhedral Particles 

Anjan Prasad, Gantapara, a.p.gantapara@uu.nl, phone: 030 - 253 24 67 

Sponsor: NWO-Vici, since May 2011 

Supervisor: Prof. dr. Marjolein Dijkstra 

Monte Carlo Simulations, Einstein Integration, Variable box-shape NPT simulations 

The shape anisotropy of colloids play a key role in determining the structure of the self-assembly. 

With the advent of experimental techniques to synthesize various polyhedral particles the interests 

in the colloidal self assembly of faceted polyhedral particles have been rejuvenated [1]. We study 

the phase behavior of such experimentally producible hard polyhedral particles using Monte 

Carlo simulations. Point symmetric hard polyhedral particles undergo an entropic phase transition 

from liquid to a periodic crystal phase with increasing pressure at constant temperature. Particles 

with asphericity ratio close to unity show the presence of a plastic crystal sandwiched between 

the liquid and crystalline phase. These plastic crystals among the faceted hard particles generally 

are HCP structures. In our simulations we have found that truncated octahedra shaped particles 

exhibiting stable plastic crystalline phase with BCC symmetry. In addition, we have also found 

some of the anisotropic shaped particles, falling in to the class of truncated cube, exhibit a rich 

phase diagram with four phases. This fourth phase is a crystal phase, differing from the close packed 

crystal structures, at intermediate pressures before melting into a plastic crystal. We determine 

the free energies of these phases using Einstein integration method and eliminate the finite size 

contributions by employing the finite size scaling. Such obtained free energies of the bulk systems 

are used to calculate the co-existing densities. 

Figure 1: Snapshots of different phases for truncated cube. The amount of truncation is quantified by the shape 

parameter s. Here s=0.411. Clock wise: Crystal structure at very high pressure (close packed), Triclinic crystal structure 

as an intermediate mesophase and the plastic crystalline phase before melting into liquid. Particles with different 

orientations have different colors. 

[1] Henzie, J et al. Nature Materials, http://dx.doi.org/10.1038/nmat3178 (2011).


Multifunctional Catalysts from Layered Colloidal Particles for Biomass 

Upgrading 

Arjen van de Glind, a.j.vandeglind@uu.nl, phone: 030 – 253 31 25 

Sponsor: Focus en Massa - Program Sustainability and Earth, since November 2009 

Supervisors: Prof. dr. Alfons van Blaaderen & dr. Arnout Imhof (SCM) and Prof. dr. Ir. Krijn de Jong & 

dr. Petra de Jongh (ACK) 

TEM, Vis-NIR spectroscopy, DSC, TGA 

Colloidal silica made from alkoxysilanes through base catalysis in water/alcohol mixtures has the 

unique property that its porosity can be tuned from ultramicroporous (< 0.3nm) to micro-, mesoand 

even macro-porous. This kind of silica can be grown onto many metal (oxides) particles as 

closed layers of 2-20 nm (or much thicker) even on noble metals as gold [1,2]. These core-shell 

systems have been developed such that colloidal stability remained over the course of the reactions, 

thus retaining the small size and dispersity of the catalysts. 

In this project forces are combined between the groups involved in nanostructured catalysts (De Jong 

and De Jongh) and the physics and chemistry of colloidal particles (Van Blaaderen and Imhof). The 

multifunctional particles can be used as building blocks for solid catalysts or as catalysts on their own. 

Gold is used as a model system and is a promising catalyst for environmental processes (e.g. low 

temperature CO oxidation[3]) as well as biomass upgrading (e.g. glycerol oxidation and selective 

hydrogenation of unsaturated aldehydes/ketones)[4]. Key problem of gold catalysts is the very low 

resistance against sintering. Silica coated particles could be a remedy. Gold nanorods (NR’s) coated 

with mesoporous silica are used as a model system to analyze the thermal stability between coated 

and uncoated gold NR’s[5]. See the figure on the right for the TEM images of freshly prepared gold 

NR’s, heat treated gold NR’s, silica coated gold NR’s 

and heat treated silica coated gold NR’s. The pictures 

show that a silica coating is able to prevent the particles 

from sintering at elevated temperatures. In situ TEM 

studies will reveal more about sinter mechanisms of 

the coated and uncoated gold particles in vacuum and 

during catalytic reaction. Catalysis studies will involve 

liquid phase selective hydrogenation of unsaturated 

cinnamaldehyde and gas phase CO oxidation. 

Figure 1: A) Freshly prepared gold nanorods. B) Gold nanorods heat treated at 200 °C. C) Gold nanorods coated with a 

mesoporous silica layer. D) Coated gold nanorods heat treated at 500 °C. 

[1] Matsuura et al, Nano letters, 2008, 8, 1, 369-373. 

[2] M.A. El-Sayed et al, Chemistry of Materials, 2003, 15, 1957-1962. 

[3] M. Haruta, Nature, 2005, 437, 1098-1099. 

[4] P.G.N. Mertens et al, Applied Catalysis A: General, 2009, 355, 176–183. 

[5] C. M. van Kats, UU PhD Thesis, 2008, Chapter 3 (www.colloid.nl). 

129

130 


Phase Behavior and Crystal Structure Prediction for Nonconvex, Irregular 

Particles with Soft Interactions 

Joost de Graaf, J.deGraaf1@uu.nl, phone: 030 - 253 81 76 

Sponsor: Utrecht University High-Potential Program and NWO-vici grant 

Supervisors: Prof. dr. Marjolein Dijkstra and dr. René van Roij 

Variable box-shape NPT simulations, Tessellation and interference algorithms 

Recent advances in the synthesis of highly anisotropic nanoparticles and colloids have created a 

demand for simulation studies of systems made up of these particles. By merging a tessellation based 

interference algorithm with a variable box-shape Monte Carlo we overcame a major challenge in 

simulating these complex particle shapes in an efficient manner. The combination has been used 

to great effect in predicting the densest-packed structures for a wide variety of particle shapes: 142 

regular convex solids and 17 nonconvex particles [1]. 

Building on the expertise developed by analyzing dense crystals, allowed us to investigate the more 

complex system of octapods, see Fig. 1, in the solution phase. We combined Hamaker-de Boer 

calculations of the van der Waals (vdW) interaction between these octapods with simulation studies 

that incorporated empirical soft-interactions. The results of these two approaches enabled us to 

describe the hierarchical self-assembly observed in the experimental systems [2] in terms of shape 

and medium dependent vdW forces. 

Currently, we are in the process of applying our methods to examine other experimentally available 

systems. Of particular interest is the richness in structures that appears when the transition between 

cubes and octahedra is made by various degrees of truncation. 

Figure 1: Schematic of the experimental (top right) hierarchical self-assembly. In toluene (I) interlocked chains are 

formed, because only configuration [right, (1)] has a sufficient vdW minimum (magenta, r = 2H). By adding the highly 

polar acetonitrile (II), the interactions become deeper (blue) and configuration [right, (2)] becomes relevant. The chains 

lengthen and undergo sideways aggregation forming a 3D superstructure, where configuration (2) governs the way in 

which the chains come together. 

[1] J. de Graaf et al., Phys. Rev. Lett. 107, 155501 (2011). 

[2] K. Miszta et al., Nature Mater. 10, 872 (2011).


Quantitative 3D force networks in static and sheared dense granular 

matter 

Jissy Jose, j.jose@uu.nl, Phone: 030 - 253 29 25 

Sponser: FOM since September 2009 

Supervisors: Prof. dr. Alfons van Blaaderen and dr. Arnout Imhof 

CLSM, SLS, Optical microscopy 

Granular materials are collections of macroscopic particles which interact with their neighbors with 

repulsive contact forces forming force chain networks. These force networks form the skeleton of 

static granular matter. In our research we want to probe these contact force on individual particles 

quantitatively in 3D real space in static dense granular system using confocal microscopy. The 

model granular system that we are using for aforementioned study consists of fluorescently labeled 

elastomeric shells of cross linked silica/siloxane filled with liquid PDMS of tunable micromechanical 

properties. It is these tunable mechanical properties of these shells that make them suitable for the 

above study as it becomes possible also to test experimentally the nature of the force network in a 

granular system under different boundary conditions. 

Recently these shells have shown some interesting phenomenon. They are the controlled buckling 

of these shells in a non-ionic surfactant solution which resulted in anisotropic bowl shaped particles 

with unprecedented control over bowl depth and unbuckling or loading of shells partly filled with 

PDMS with different oils like silicone oil (octamethylcyclotetrasiloxane) and hydrocarbon oils. 

Moreover buckling of thin shells also leads to interesting coffee bean shape. 

Figure 1: Confocal images of fluorescently labeled oil filled shells at two different concentrations of non-ionic surfactant 

(a) 0.48 v/v% and (b) 8.3 v/v%. Buckled shells partly filled with PDMS in functional oils (c) octamethylcyclotetrasiloxane. 

Coffee bean shape resulted from buckling of thin silica / siloxane shell. 

131

132 


Molecular control of directional colloidal interactions 

Marlous Kamp, M.Kamp@uu.nl, phone: 030 - 253 23 63 

Sponsor: NWO-CW, since July 2010 

Supervisor: Prof. dr. Alfons van Blaaderen and dr. Arnout Imhof 

CSLM, SEM 

Patchy particles are colloids with anisotropic inter-particle interactions [1]. Patchy particles are 

currently an active field of research in both experiments and simulation. This research is aimed at the 

synthesis and study of patchy silica particles with amongst others thermally switchable interactions. 

The interactions will be based on the presence or absence of steric stabilization. Colloids can exhibit 

a temperature-dependent gelation transition in a well-chosen apolar solvent [2], when grafted with 

linear aliphatic alcohols or acids. The gelation is caused by the freezing of a single layer of alkane 

molecules on the particle surface, which increases Van der Waals attractions (e.g. octadecanol coated 

silica in hexadecane). 

We will attempt to combine this gelation transition with techniques for producing patchy particles. 

An example of such a technique is grafting of a close-packed crystal. The SEM image below shows 

patchy particles created via such a method. It shows silica particles grafted while packed in a crystal. 

The contact areas of the particles in the crystals were not modified. These areas are visible as dark 

spots, because small holes have been etched at these spots using a dilute HF solution. 

[ ] Doppelhauer, G. et al. Self-assembly scenarios of patchy colloidal particles in two dimensions. J Phys: Cond Mat 22 (2010), 104105. 

[2] Roke, S. et al. Surface molecular view of colloidal gelation, PNAS 103 (2006), 13310.


Sample Preparation and Applications for integrated Laser and Electron 

Microscopy (iLEM) 

Matthia Karreman, M.A.Karreman@uu.nl, phone: 030 - 253 34 49 

Sponsor: STW, since December 2008 


iLEM, FM, TEM 

The integrated Laser and Electron Microscope (iLEM) combines a fluorescence microscope (FM) 

and a transmission electron microscope (TEM) in one set-up. The regions of interest in the sample 

are identified with the FM based on localization of fluorescent probes, and subsequently these areas 

can effortlessly be retraced in the TEM and imaged at high resolution [1]. The iLEM demands 

samples suitable for both FM and TEM imaging. Therefore, conventional methods for the preparation 

of biological material are not applicable. During my research we set out to develop and optimize 

sample preparation methods for iLEM [2,3]. Furthermore, the unique possibilities of the iLEM as 

a research tool were demonstrated in the field of both Life and Material Science [3,4]. 

In collaboration with the group of Prof. dr. ir. B.W. Weckhuysen, the iLEM was employed to correlate 

the catalytic activity of Fluid Catalytic Cracking (FCC) particles to their ultrastructure [4,5]. The 

catalytically active areas in the FCC particles were selectively stained based on the fluorescent 

products of 4-fluorostyrene oligomerization [5]. Next, these areas were retraced in the TEM and 

imaged at high resolution (Figure 1) [4]. 

In life science, the iLEM is used to study Facio Scapulo Humeral muscle dystrophy (FSHD). In 

the near future, we hope to identify specific molecular markers for this disease. This will allow us 

to navigate with the iLEM to the diseased cells within muscle dystrophies of FSHD patients and 

gain more insight in the progression of FSHD on a cellular level. 

Figure 1: Imaging FCC particles with iLEM 

[1] A.V. Agronskaia et al, J. Struc. Biol. 2008. 

[2] M.A. Karreman et al, Biol. of the Cell, 2009. 

[3] M.A. Karreman, E.G. Van Donselaar et al, Traffic, 2011. 

[4] M.A. Karreman, I.L.C. Buurmans et al, Angew. Chem. Int. Ed., in press. 

[5] I.L.C. Buurmans et al., Nature Chemistry, 2011. 

133

134 


Non-linear Spectral Imaging of Fungi 

Helene Knaus, H.Knaus@uu.nl, phone: 030 - 253 28 23 

Sponsor: STW, since February 2009 

Supervisor: Professor dr. Han A.B. Wösten and Professor dr. Hans C. Gerritsen 

Autofluorescence, two-photon excitation, spectral detection, fungi 

Fungi are well known as food (e.g. mushrooms, cheeses), and are utilized to produce industrial and 

pharmaceutical proteins. Both are multibillion industries requiring quality control of the mycelium 

and the mushroom. With non-linear spectral imaging we want to establish a new and fast method 

to determine freshness, the absence of pathogens, and the productivity. Furthermore, one can target 

more fundamental questions, like differentiation within fungal mycelium. 

In non-linear spectral imaging, the contrast in the specimen arises from the autofluorescence 

signal, excited by the simultaneous absorption of two near-IR photons. Some specific molecules 

within the fungi are endogenous fluorophores. For example, NADH autofluorescence contains 

information on the metabolic state of the fungi and the melanin is responsible for the browning 

of the mushroom. Since excitation is limited to focal volume, the benefits of nonlinear imaging 

include intrinsic 3-dimensionality, no out-of-plane photobleaching, and diffraction-limited spatial 

resolution of 0.3 μm, making it an optimal technology to study microbial metabolism at a cell level. 

Figure 1: Non-linear spectral image of the white button mushroom (A. bisporus).

Concentrated dispersions of rod-like particles 

Anke Kuijk, A.Kuijk@uu.nl, phone: 030 - 253 23 15 

Sponsor: UU since December 2007 


Colloidal synthesis, TEM, confocal fluorescence microscopy 


Rods in dispersion have interesting phase behavior. In addition to the well-known gas, liquid en 

crystal phases of colloidal spheres, anisotropic particles are also able to form liquid crystalline phases 

(nematic and smectic). In order to study these phases, we developed a new monodisperse colloidal 

model system. Rod-like silica colloids were successfully made using a wet chemical synthesis. This 

allowed us to produce many particles at once, which is needed in order to study the phase behavior 

of concentrated dispersions of rods. Because the particles are made of silica, standard techniques can 

be used to label them with a fluorescent dye and study them using confocal microscopy. 

As mentioned before, isotropic, nematic and smectic liquid crystal phases are present in the phase 

diagram of rod-like systems. Using our new system, we study these phases in real-space and real-time 

using confocal microscopy. Additionally, the effect of external fields on the phase behavior of the 

rods is studied. Electric fields, shear and templates are used to bring the system out of equilibrium 

in a controlled way. A general effect of these fields is that they can be used to align the particles at 

densities where they would normally form an isotropic phase. This way it is possible to control the 

direction of alignment and to create dense phases with a reduced amount of defects. 

Figure 1: (a) TEM-image of monodisperse silica rods. (b) Confocal microscopy image of rods in a smectic phase on and 

beside a template consisting of trenches. Scalebar indicates 5 μm. 

135

136 


Effective Interaction of Nanoparticles 

Bas Kwaadgras, B.W.Kwaadgras@uu.nl, phone: 030 - 253 23 20 


Supervisors: Prof. dr. ir. M. Dijkstra and dr. R. van Roij 

Large Matrix Inversion and Eigenvalue Calculations, Variable Box-Shape NPT Simulations, Einstein Integration 

The effective interaction of nanoparticles is still a little-explored field. Models used for larger 

colloids fail here, mainly due to finite-size effects and the anisotropic nature of nanoparticles, and 

only rudimentary models exist for them. 

A promising method, the Coupled Dipole Method (CDM), treats the nanoparticles as being built 

up out of atoms that are being modeled as an electron bound to the nucleus by a harmonic force. 

These atoms thus act as induced dipoles and can interact with each other and possibly an external 

electric field, where all many-atom interactions are taken into account by the CDM. Using a 

Hamiltonian approach[1,2], we can calculate the frequencies of the eigenmodes of the system, 

and we can subsequently gain the ground state interaction energy by simply summing these mode 

frequencies. The same Hamiltonian approach also yields the electrostatic potential energy of the 

particle in an external electric field as well as the corresponding polarizability of the nanoparticle. The 

CDM requires manipulations of a matrix that is typically large (to be precise, it is a 3Nx3N matrix, 

where N is the number of atoms) and optimized algorithms have to be used to achieve reasonable 

numbers of atoms. However, the number of atoms the CDM can (practically) handle is below ~105, 

which is unfortunately slightly below typical experimental system sizes. A possible solution to this 

problem is provided by noting that the “atoms” that the CDM models do not necessarily have to 

correspond to real, physical atoms, but could instead correspond to simply “chunks” of polarizable 

matter. The “atomic” polarizability assigned to these generalized “atoms” can be calculated using 

the permittivity (contrast) of the substance being modeled. One of the current aims of my research 

is to investigate how accurate this approach is. 

Figure 1: Nanoparticles can be modeled as somewhat spherical clusters of atoms, for example on an fcc grid. 

[1] M. J. Renne and B. R. A. Nijboer, Chem. Phys. Lett. 1, 317 (1967). 

[2] B. W. Kwaadgras, M. Verdult, M. Dijkstra, and R. van Roij, J. Chem. Phys. 135, 134105 (2011).


The glass transition in a colloidal model system with long-range repulsions 

Marjolein van der Linden, M.N.vanderLinden@uu.nl, phone: 030 - 253 81 76 

Sponsor: NWO Toptalent, since September 2008 

Supervisors: Prof. dr. A. van Blaaderen, Prof. dr. ir. M. Dijkstra 

Confocal fluorescence microscopy, Monte Carlo simulations 

In this research project, we investigate the glass transition in a colloidal model system with longrange 

repulsions through the combined use of confocal microscopy and computer simulations. 

Experimentally, we study two types of fluorescently labelled colloidal particles that exhibit long-range 

repulsive interactions. One model system consists of sterically stabilised polymethylmethacrylate 

(PMMA) particles dispersed in a mixture of cyclohexylbromide (CHB) and cis-decalin. The second 

model system consists of silica particles with a layer of apolar molecules attached to their surface, 

allowing for the particles to be suspended in a relatively apolar solvent, such as cyclohexylchloride 

(CHC). 

By changing the salt concentration in the dispersion the interactions can be chosen in the range 

between hard-sphere-like and long-range repulsive. Because the charged colloidal particles are 

dispersed in an apolar liquid instead of the usual polar liquids such as water, the model system can 

be tuned to have long-range repulsive interactions even in the case of micron-sized particles. Such 

a system, for which the phase behaviour is known to be very different from that of hard spheres, 

has hardly been studied in connection with the glass transition. We investigate the glass transition 

in this model system using both experiments (Confocal Laser Scanning Microscopy (CLSM)) and 

computer simulations. 

We study the effect of several parameters on the ability of the system to form glassy structures: 

the size/charge polydispersity of the particles, the presence of clusters in the system, the Debye 

screening length (indicating the thickness of the electrical double layer or ‘softness’ of the potential), 

the compression speed, and gravity. 

137

138 


Phase transition of rod-like particles with long ranged repulsive force 

Dr. Bing Liu, b.liu@uu.nl, phone: 030 - 253 23 63 

Sponsor: FOM, since December 2010 


CLSM, TEM 

Hard rod-like colloidal particles are known to form liquid crystal phases (nematic and smectic) if 

sufficiently long. With long-ranged repulsive forces added, it has recently been found by us that 

systems of anisotropic particles (dumbbells) can also form plastic crystal phases where positional 3D 

order is long-ranged but rotational order is not. In these systems there is still long-time rotational 

diffusion of the particles.. An external electric field can be used to manipulate the rotation of such 

systems. Studying such phase transitions and how to manipulate them is not only interesting from 

a fundamental point of view but also important for applications utilizing collective phenomenon 

arising either with rod-like particles with a size of the wavelength of visible light or for particles 

in the nano-regime such as metal en semiconductor rods. 

Recently, a new model system of micrometer-size silica rods with the possiblitiy to induce long 

ranged repulsive forces between them has been developed by our group (Figure 1a), which provide 

the opportunity to study the above mention behavior in real space and real time by confocal 

microscopy. We found that such silica rods can indeed also form the interesting plastic crystal phase 

in low dielectric constant media (Figure 1b). In addition we studied how the phase behavior can be 

controlled by the addition of salt or the application of an external electric field (figure 1c). Through 

real space analysis, we can obtain a detailed microscopic understanding of the phase behavior, and 

investigate the potential and optimal conditions for possible applications as well. 

Figure 1: a) TEM image of monodispersed silica particles; fluorescent silica rods form b) plastic crystal phases without an 

external electric field and c) a crystal phase with an external field (bar 5 micron).

Phase behavior of snowmen shaped particles 

Kristina Milinkovic, K.Milinkovic@uu.nl, phone: 030 - 253 81 76 

Sponsor: NWO-VICI, since April 2009 

Supervisor: Prof. dr. ir. Marjolein Dijkstra 

Monte Carlo simulations, Einstein integration 


Recent progress in the synthesis of anisotropic colloidal particles has significantly increased the 

potential for forming novel and complex crystalline structures. One such class of anisotropic 

particles is the asymmetric dumbbell, or ‘snowmen’ shaped particle, consisting of two spheres of 

different diameters rigidly fused together at their surfaces. These particles have the potential to 

form crystalline structures similar to those predicted for binary sphere mixtures [1], without the 

potential problems of phase separation. In this project, we use Monte Carlo simulations to examine 

the phase behavior of this system through the full range of constituent sphere diameter ratios, from 

the simple hard sphere to the symmetric dumbbell. 

Compression of isotropic phases in computer simulations results in crystallization only for small and 

very large diameter ratios. For intermediate ratios, we generate potential snowmen crystals based 

on the binary crystalline structures predicted for hard spheres, and investigate their relative stability 

using free energy calculations. We find stable plastic crystalline phases for small diameter ratios, and 

a range of aperiodic crystalline phases to be stable throughout the phase diagram. 

Figure 1: Some of the investigated crystal structures. 

[1] L. Filion and M. Dijkstra, Physical Review E 79, 046714 (2009). 

139

140 


Investigation of Laser-Induced DNA Damage in Nonlinear Microscopy 

Dr. Oleg Nadyarnykh, o.nadyarnykh1@uu.nl, phone: 030 - 253 12 44 

Sponsor: STW, since February 2010 

Supervisor: Prof. dr. Hans C. Gerritsen 

Multiphoton Excitation Microscopy, Optical Microscopy, Microscopy/Spectroscopy, Fluorescence Microscopy 

There has been increased interest in development of high-resolution optical imaging of tissue 

structure in vivo for diagnostics and monitoring of cancer and other disorders. Nonlinear optical 

modalities (multi-photon absorption, second and third harmonic generation) achieve high xy 

resolution (0.3μm) at near-IR wavelengths (700-1000nm). While second harmonic signal contrast 

arises in living tissue from non-centrosymmetric protein arrays (collagen, myosin), additional contrast 

is provided below 800nm by autoflurescence of NADH, FAD, melanin and various lipoproteins. 

Several groups including us are developing nonlinear imaging via miniaturized scanning systems 

for minimally invasive optical biopsy. However, for successful transition from laboratory bench to 

clinics biological safety must be considered as high peak power femtosecond laser pulses can damage 

tissue and cells. Under tight focusing photon density is high enough for simultaneous absorption 

of three and two photons by DNA. The induced damage is similar to that from UV exposure that 

causes formation of cyclobutane-pyrimidin-dimers (CPDs) in DNA. Inaccurate repair of DNA 

damage results in mutations that might lead to cancer. 

Recently, we have investigated the mechanisms of DNA damage introduced in cells in vitro using 

fluorescent antibodies against CPDs for quantification. We further investigated the extent of CPD 

damage with respect to peak intensity of the laser, excitation wavelength, pulsewidth at focal plane 

varied with custom-built grating pair, and pixel dwell time. Our findings allowed us to identify 

relatively safe imaging regimes and produce a model for estimation of a (relatively low) carcinogenic 

risk from an optical biopsy. 

Currently, we are extending our study to DNA damage in tissues. 

Figure 1: Left panel: Fluorescence signal from antibodies shows the CPD damage localized in cell nuclei of rat stomach tissue, 

the undamaged area is in the bottom right corner. Right panel: Fluorescence from the co-localized DAPI staining showing 

all the cell nuclei.

Entropy-Driven Phase Transitions in Colloidal Systems 

Ran Ni, R.Ni@uu.nl, phone: 030 - 253 24 67 

Sponsor: NWO-Vici, since September 2008 

Supervisor: Prof. dr. Ir. Marjolein Dijkstra 


Monte Carlo simulations, Event Driven Molecular Dynamics simulations, Variable box-shape NPT simulations 

and Einstein integration 

We studied a system of colloidal hard superballs, whose shape interpolates smoothly between two 

Platonic solids, namely the octahedron and the cube via the sphere. By performing free-energy 

calculations, we determine the phase diagram of colloidal hard superballs as shown in Fig.1a. Of 

particular interest is the discovery of a stable body-centered cubic (bcc) plastic crystal phase for 

octahedron-like superballs. Surprisingly, our results show that the bcc and fcc plastic crystal phases 

are not thermodynamically stable for the flat-faced hard octahedra and hard cubes, respectively, 

which suggests that the rounded corners of superballs play an important role in stabilizing the 

rotator phases [1]. 

In addition, in experiments, it was found that the hard superballs form a simple cubic (sc) crystal in 

polymer solutions [2]. By free volume calculations, we found that at the high polymer concentration 

limit where the experiments are normally performed, the detailed shape of the superballs and the 

size of polymers play significant roles in the crystallization of superballs. In order to obtain an sc 

crystal, one should use small polymers and the shape of superballs should be in between that of 

cubes and spheres, which agrees very well with experiments. 

Moreover, motivated by recent experiments [3], we also studied the sedimentation of hard rods 

on hard walls with templates as shown in Fig. 2b. We found that the existence of templates on the 

hard wall significantly improves the formation of smectic phase on the wall, while the sediments 

on hard walls without templates are disordered. This result matches well with the experimental 

observations. Furthermore, we plan to study whether or not the formation of the smectic phase 

on templates is via complete wetting. 

[1] R. Ni, et al. submitted arXiv:1111.4357v1 [cond-mat.soft]. 

[2] L. Rossi, et al. Soft Matter, 7, 4139 (2011). 

[3] A. Kuijk, PhD thesis, Utrecht University (2012). 

[4] Y. Jiao, et al. Phys. Rev. E 84, 069902 (2011). 

Figure1: (a) Phase diagram for hard superballs in 

the Φ (packing fraction) versus 1/q representation 

where q is the deformation parameter. Here the 

C1 and C0 crystals are defined in Ref. [4], where 

the particles of the same color are in the same 

layer of stacking. The solid diamonds indicate the 

close packing, and the locations of triple points 

are determined by extrapolation as shown by the 

dashed lines. (b) Sediments of hard rods with L/D 

= 4.2 and gravitational length lG = D, where L and 

D are the length of the cylindric part and the width 

of the particle, respectively. Here the blue cuboids 

are the templates on the bottom. 

141

142 


Crystals of Crystals of Nano-Crystals 

Bart de Nijs, B.deNijs@uu.nl, phone: 030 - 253 12 87 

Sponsor: NWO, since Nov 2008 


3D-TEM, Cryo-TEM, Nanoparticle synthesis, Emulsification 

Self-assembly of nanoparticles within a spherical confinement results in a multi scale system which 

can combine Nano-scale properties e.g. Quantum confinement and localized Plasmon resonance 

with colloidal properties e.g. Bragg-reflection. By evaporating emulsion droplets of low boiling 

oils in water we get a shrinking spherical confinement for hydrophobic media. When loaded with 

nanoparticles and evaporated the droplets will shrink until only the nanoparticles and the surfactant 

are left. Since these nanoparticles are hydrophobic they are compressed by the interfacial tension 

into a large super particle. If we freeze dry these super particles and look at them with 3D-TEM 

we can determine their crystal structures as is shown in fig. 1. 

The goal of this research is to make these assemblies from monodisperse emulsions resulting in a 

uniform size distribution of these super particles and let them self-assemble into larger superstructures, 

as is shown in figure 2. 

Figure 1a: Electron tomogram slice of a nanoparticle assembly showing the inwards triangular pyramid shapes of the crystal 

domains (scalebar is 30 nm). 1b: 3D plot of the assembly with each domain a different color ( none crystalline particles are 

not shown). 1c: Schematic representation of an icosahedron with a triangular domain pointing inwards. 

Figure 2a: Self-assembled superstructure of super particles of CoFe 2 O 4 nanoparticles (scalebar is 1 µm).

Regular colloidal clusters of non-spherical particles 

Bo Peng, B.Peng@uu.nl, Phone: 030 - 253 23 20 

Sponsor: EU nanodirect since September 2008 



Colloid synthesis, TEM, SEM, Confocal laser scanning microscopy (CSLM), Light scattering (SLS) 

The preparation and properties of non-spherical colloidal particles is an important subject of 

study, because it will lead to new materials, the properties of which can be better controlled. Nonspherical 

particles can be fabricated using the swelling method. This method needs to be extended 

to particles of Polymethyl Methacrylate (PMMA), because this allows them to be refractive index 

matched and studied with confocal laser scanning microscopy (CSLM). Then the self-assembly of 

non-spherical particles can be studied, for example by using the literature method of Manohan & 

Pine. It will also be tried if the method can be extended to nanocrystals. 

In a later stage, the system that will be studied are nanocrystals carrying a permanent dipole moment. 

In this case an external electric field will be used to align and group the particles. The goal of the 

second part of the project is to study the phase behavior of these systems at high concentrations 

using quantitative real-space analysis at the single particle level with confocal microscopy, as well 

as scattering methods. Also, we want to focus on the behavior of these systems under the influence 

of an external electric field. 

Figure 1: Cluster configurations from non-spherical particles and spherical particles, and corresponding computer simulation 

results. The scales bar is 2 µm. 

143

144 


Monte-Carlo Simulations of Confined Two-Dimensional Hard Octapods 

Dr. Weikai Qi, w.qi@uu.nl 

Sponsor: UU, since August 2011 

Supervisor: Prof. dr. ir. Marjolein Dijkstra 

Monte-Carlo Simulations, Variable box-shape NPT simulations 

Self-assembly of Octapods nanocrystals in three dimensional have been studied in experiment and 

Monte-Carlo simulations [1]. We studied self-assembly and phase behavior of two-dimensional 

confined hard octapods by Monte-Carlo simulations. In the simulations, each octapod consists of 

four hard spherocylinders, which overlap in the center. The spherocylinder-like octapod is defined 

by the length to diameter ratio L/D of the spherocylinders (Figure 1). The densest-packed crystal 

structure can be predicted via variable box shape Monte Carlo simulation [2]. The densest-packed 

crystal structure of confined octapods for various shape factors L/D is shown in Figure 2. For L/ 

D>2.0, the particles is an octapod and the packing fraction is a square phase. Similar square phase 

is also observed in experiment of L. Manna’s group. For L/D


Phase Behavior of Hard Polarizable Colloidal Rods in an External Electric Field 

Thomas Troppenz, t.troppenz@uu.nl, phone: 030 - 253 57 21 


Supervisor: Prof. dr. ir. Marjolein Dijkstra and dr. Rene van Roij 

Monte Carlo simulations, Nematic liquid crystalline theory, Onsager theory 

Dispersions of polarizable colloidal spheres with a dielectric constant mismatch with the surrounding 

solvent acquire a dipole moment in an external electric field. The resulting dipolar interactions 

between the colloids lead to the formation of string-like clusters where the dipoles are aligned 

head to toe. As the rheological properties can be tuned by the electric field, these so-called electrorheological 

fluids have potential use in industrial applications such as hydraulic valves, brake fluids, 

and bullet-proof vests. To a first order approximation the phase behavior of these suspensions is welldescribed 

by a dipolar interaction between point dipoles, which are aligned with the applied field 

and located in the center of each colloidal sphere. The phase diagram is well studied and displays a 

string fluid at low packing fractions and low field strengths and a body-centered-tetragonal crystal 

phase at high field strength. 

The phase behavior of anisotropic colloidal particles has received less attention and is the focus 

of our work. We study the behavior of such a system of polarizable colloidal rods subject to an 

external electric field through Onsager theory as well as Monte-Carlo simulations. In addition to 

the well known nematic, smectic and crystal-phases that a system of hard non-polarizable rods can 

realize, we probe the formation of a string fluid as well as that of columnar and other crystal phases 

in accordance with recent experiments as well as earlier simulations. 

Figure 1: a) Distribution of induced molecular dipoles in a pair of polarizable colloidal rods. b) Snapshot of the K2 crystal 

phase that a system of polarizable colloidal rods can realize at high field strengths and packing fractions. 

145

146 


Two-photon microscopy and Spectral phasor to monitor NADH (free/bound) 

and FAD in normal and cancer cells in 3D culture 

Dr. Hoa Truong, h.h.truong@uu.nl, phone: 030 - 253 28 23 

Sponsor: STW, since March 2011 

Supervisor: Prof. dr. Hans C. Gerritsen 

Multiphoton excitation microscopy, fluorescence microscopy, spectroscopy, cell culture 

Nicotinamide Adenine Dinucleotide (NADH) and Flavin Adenine Dinucleotide (FAD) are 

important coenzymes that play important role in regulating metabolism. It has been described 

by various groups that auto-fluorescence property of NADH and FAD can be exploited to study 

cancer progression and cell death [1,2] via two-Photon Fluorescence Lifetime imaging (FLIM) 

system. In the general direction, we developed a unique approach of imaging and measuring NADH 

(free in cytoplasm and bound to enzyme) and FAD in 3D culture by combining two-photon 

microscopy with anisotropy and spectral phasor (representing the spectra by polar representation 

for image analysis). Our goal is to exploit this technique to characterize cancer and non-cancer 

cellular spheroids (cell aggregates) by un-mixing and quantifying the intrinsic fluorphores based 

on their emission spectrum. Furthermore, we can employ NADH as possible apoptosis biomarker 

for 3D culture drug screening and invivo imaging of tumor model. This is more feasible approach 

than standard histopathological assessment which require fixation which likely alter fluorescence 

lifetimes compared with unfixed tissue. 

Figure 1. Optical sectioning of CHO cell spheroid with multiphoton 

excitation. The spheroid of ~500 um was excited with 740 nm 

in which NADH and FAD can be detected. Shift in the spectrum 

correlates with the changes in depth. Furthermore, shift from blue 

color (NADH) to yellow color (FAD) is observed. (A) Outer layer of 

spheroid (B) Inner layer of the spheroid (C) Core of the spheroid. 

(D) Spheroid of ~300-500 um contains several layers of cells at 

different stages of growth and activities. 

[1] Skala MC et al. In vivo multiphoton fluorescence lifetime imaging of 

protein-bound and free nicotinamide adenine dinucleotide in normal 

and precancerous epithelia. J Biomed Opt. 2007 Mar-Apr;12(2):024014. 

[2] Wang HW et al. Differentiation of apoptosis from necrosis by dynamic 

changes of reduced nicotinamide adenine dinucleotide fluorescence 

lifetime in live cells. J Biomed Opt. 2008 Sep-Oct;13(5):054011.

Predicting Crystal Structures of Patchy Particles 

Dr. Teun Vissers, t.vissers@uu.nl, phone: 030 - 253 31 25 

Supervisor: Prof. dr. ir. Marjolein Dijkstra* 

Monte Carlo Simulations, Einstein Integration 


Colloids and nanoparticles with attractive patches on their surface can establish highly directional 

bonds, which allows them to form structures that cannot always be so easily realized using isotropic 

interactions. Both experimentally as well as in computer simulations, such structures are found [1-3]. 

However, there is not yet a reliable method to a priori predict stable crystal structures of interacting 

patchy particles. We employ a powerful combination of variable box shape Monte Carlo computer 

simulations [4] and free energy calculations using thermodynamic integration schemes [5]. In the 

first one, the unit cells of possible crystal structure candidates are computed in a box containing a 

small number of particles. For a given pressure, temperature and number of particles, the particle 

positions, orientations and the shape and dimensions of the box are allowed to fluctuate. From the 

candidate structures, we proceed with free energy calculations to determine their stability. 

Figure 1: An example of a crystal structure of janus particles inside a ‘floppy box’ with periodic boundary conditions. These 

particles consist of two hemispheres. The hemispheres drawn in red attract each other via square well attractions. The 

hemispheres drawn in blue only interact via hard-core repulsions. Note that the unit cell is copied a number of times in 

all three directions to show the crystal structure more clearly. 

[1] Q. Chen et al., Nature, 469, 381 (2011) 

[2] F. Sciortino et al., Phys. Rev. Lett., 103, 237801 (2009). 

[3] E.G. Noya et al., J. Chem. Phys., 132, 234511 (2010) 

[4] L. Filion et al., Phys. Rev. Lett. 103, 188302 (2009). 

[5] C Vega et al., J. Phys.: Condens. Matter 20, 153101 (2008). 

*In collaboration with Prof. Dr. Francesco Sciortino, Sapienza – Università di Roma. 

147

148 


Miniaturized nonlinear microscope with spectral detection for in vivo tissue 

imaging 

Johan van Voskuilen, c.j.vanvoskuilen@uu.nl, phone: 030 - 253 23 44 

Sponsor: STW, since September 2009 


Multiphoton excitation microscopy, Optical microscopy, Fluorescence microscopy 

The procedure of taking biopsies is slow, often it takes a week before results are available, and often 

painful. For this project we envision to develop an optical biopsy method. We design and build a 

miniaturized microscope for performing these optical biopsies. Two different nonlinear microscopy 

techniques are used that use contrast based on two photon excitation of fluorescence and second 

harmonic generation respectively. These techniques provide contrast in living tissue without applying 

stains. Signals are detected from, amongst others, auto-fluorescence of metabolic products (e.g. 

NADH and FAD), pigments (melanin), and second harmonic generation of connective tissue 

(collagen). The microscope utilizes a miniaturized scanner that drives a fiber tip with an objective lens 

attached to it. The scanner is fitted into a 3mm diameter tube and can be operated at a 1Hz frame 

rate. The focal spot is scanned in a circular pattern in the xy-plane and z-scanning is accomplished 

by a piezo drive. The scanner is fiber coupled to the rest of the microscope using a special “double 

clad photonic crystal” fiber. This facilitates signal guiding of both single-mode infrared excitation 

pulses and broadband multimode visible emission. Pulse broadening of the excitation light due 

to dispersion in the fibre is pre-compensated by a custom built grating compensator. Emission is 

detected using a custom built spectrograph with a sensitive EM (electron multiplication) CCD for 

fast (10 kHz spectral rate) spectral detection. 

Figure 1: Photograph of the miniaturized microscope scanner.


Bonding Assembled Colloids without Loss of Colloidal Stability 

Hanumantha Rao Vutukuri, H.R.Vutukuri@uu.nl, phone: 030 - 253 23 15 

Sponsor: FOM, Nanodirect, since Oct 2006 


Confocal fluorescence microscopy, SEM 

In recent years, the diversity of self-assembled colloidal structures has strongly increased as it is 

fueled by a wide range of applications in materials science and also in soft condensed-matter 

physics. Some potential applications include photonic band-gap (PBG) crystals, materials for 

plasmonic devices, high- efficiency energy conversion and storage, miniature diagnostic systems, 

desalination, and hierarchically structured catalysts. Three dimensional colloidal crystals with mostly 

close packed (randomly or fcc stacked) have been fabricated via various methods. Recently, many 

methods are currently being developed further to fabricate more diverse crystal symmetries and 

non-close packed structures by tuning the interaction between the particles, namely: oppositely 

charged interactions, external electric fields, and/or non-spherical shapes. However, the structures 

thus formed are vulnerable to capillary forces that arise when the solvent is evaporated and to many 

other post-treatment steps, especially when the particles are non-close packed. We have developed a 

simple in situ thermal annealing method to permanently fix non-close and close-packed polymeric 

structures, so that they easily survive a subsequent drying step without loss of colloidal stability 

[1]. Furthermore, we have implemented our bonding method to four different non-close packed 

assemblies and one close-packed structure [1]. 

Figure 1: Labyrinth structure consisting of 2D particle sheets oriented in the direction of the applied field (field is 

perpendicular to the imaging plane) at a packing fraction of about 20 %. a, Confocal microscope image shows a cross 

section through a labyrinth pattern in the absence of the applied electric field. b, Rendered particle coordinates revealing 

the three-dimensional network. Scale bar is 10.0 μm. 

[1] H. R. Vutukuri et al. Bonding Assembled Colloids without Loss of colloidal Stability, Advanced Materials, accepted. 

149

150 


Smart Microscopy of Biological Tissues 

Tim van Werkhoven, T.I.M.vanWerkhoven@uu.nl, phone: 030 - 253 28 23 

Sponsor: STW, since 2009 

Supervisor: Prof. dr. Christoph Keller and Prof. dr. Hans Gerritsen 

Multiphoton Excitation Microscopy, Adaptive Optics, Wavefront Sensing 

Microscopy has become increasingly more important in biological and biomedical work. This is to a 

great extent due to the development of advanced imaging methods such as confocal microscopy[1,2] 

and multi-photon excitation microscopy[3] that provide 3-D imaging in (optically thick) specimens. 

At present, multi-photon excitation microscopy is the technique of choice for high-resolution 

in-vivo imaging. Unfortunately, the use of these techniques is seriously hampered by specimeninduced 

aberrations[4] that result in reduced depth penetration, loss of spatial resolution, and 

increased phototoxicity (Fig. 1). 

Current implementations of adaptive optics[5] (AO) provide evidence that AO can significantly 

improve image quality, depth penetration, and spatial resolution while reducing phototoxicity in 

scanning microscopy[6]. However, severe speed limitations render them impractical for real-life 

applications. 

In this project we focus on the development of fast, active compensation methods for specimeninduced 

wavefront aberrations. High compensation speeds will be realized by using adaptive optics in 

combination with smart predictive algorithms that take into account all system properties including 

the scanning nature of the acquisition, the dynamic properties of the deformable mirror based AO 

and the nature of the optical optimization. 

We are currently investigating which wavefront sensing methods are suitable for measuring sample 

induced wavefront aberrations in a microscopy context. 

Figure 1: Problem illustration: without sample (left), a plane wave can be 

focused into a diffraction limited spot. In the presence of a perturbing 

sample (right), the focus breaks up leading to loss of signal and resolution. 

[1] J. B. Pawley and B. R. Masters. Handbook of Biological Confocal Microscopy. Journal of Biomedical Optics, 13(2):029902+, 2008. 

[2] David M. Shotton. Confocal scanning optical microscopy and its applications for biological specimens. Journal of Cell Science, 

94(2):175–206, October 1989. 

[3] W. Denk, J. H. Strickler, and W. W. Webb. Two-photon laser scanning fluorescence microscopy. Science, 248(4951):73–76, April 1990. 

[4] M. Schwertner, M. J. Booth, and T. Wilson. Specimen-induced distortions in light microscopy. Journal of Microscopy, 228(1):97–102, 

October 2007. 

[5] Robert K. Tyson. Principles of adaptive optics. Series in optics and optoelectronics. CRC Press, Boca Raton, FL, 3 edition, September 

2011. 

[6] Martin J. Booth. Wavefront sensorless adaptive optics for large aberrations. Optics letters, 32(1):5–7, January 2007.

Theoretical Chemistry 



151

152 


Spin transitions in metal complexes: Theoretical study using ab initio and 

density functional theory methods 

Zahid Rashid, Z.Rashid@uu.nl, phone: 030 - 253 27 29 

Sponser: Higher Education Commission of Pakistan 

Supervisor: Dr. Joop H. van Lenthe 

Complete Active Space SCF method (CASSCF), CASSCF with multiconfigurational second-order perturbation 

theory (CASPT2), Coupled Cluster method (CCSD(T)), Density Functional Theory (DFT). 

Transition metal complexes in which the spin-state of the central metal ion can be altered by 

an external perturbation like change in temperature, pressure, irradiation by light or magnetic 

field have become an object of intense experimental and theoretical investigations due to their 

possible use in memory and display devices and as molecular switches. The compounds that show 

this phenomenon are mainly the complexes of Fe(II) and to a lesser extent Fe(III), Mn, Co and 

Ni complexes. The spin-transition in these complexes is generally accompanied by change in the 

metal-ligand bond distances. The low-spin (LS) state of, e.g. Fe(II) in an octahedral ligand field 

(S=0) leaves the antibonding iron eg-orbitals unpopulated compared to the high-spin (HS) state 

(S = 2) where each of the two eg-orbitals are singly occupied. As a consequence the HS state has 

significantly longer iron ligand distances than the LS state. 

The short metal-ligand bond distances in LS complexes result in the higher metal-ligand binding 

energy and thus higher metal-ligand stretching frequencies as compared to the HS complexes. 

Therefore, any method that can calculate the vibrational properties of these complexes, e.g., Infrared 

(IR) and Raman spectroscopy, can be used to study the spin-transition in these complexes. Ab 

initio quantum mechanical methods and the density functional theory provide an opportunity to 

study this phenomenon quantitatively. Our study will be focussed on the spin-transition in the 

Fe(II) complex of bapbpy ligand. To understand the nature of the spin-transition in this complex 

the vibrational modes, the relative stability of LS and HS species, the effect of the (possible) ligandto-metal 

charge transfer and the metal-to-ligand π back donation on the relative stability will be 

studied using CASSCF, CASPT2, CCSD(T) and density functional theory methods. Later the 

calculations will be extended to Mn, Co and Ni complexes of bapbpy.

Techniques Index 

153

Author Index 

Author Index 

Surname, Initials Name E-mail Page 

PhD students 

Angelici, C. Carlo C.Angelici@uu.nl 24 

Aramburo-Corrales, L.R. Luis L.R.Aramburocorrales@uu.nl 25 

Au, Y. S. Yuen Y.S.Au@uu.nl 26 

Baars, R.J. Roel R.J.Baars@uu.nl 104 

Basauri Molina, M. Manuel M.BasauriMolina@uu.nl 94 

Belli, S. Simone S.Belli@uu.nl 124 

Berg, R. van den Roy R.vandenBerg1@uu.nl 27 

Berkum, S. van Susanne S.vanBerkum@uu.nl 105 

Besseling, T.H. Thijs T.H.Besseling@uu.nl 125 

Bij, H.E. van der Hendrik H.E.vanderbij@uu.nl 38 

Boga, D.A. Dilek D.A.Boga@uu.nl 29 

Boneschanscher, M. P. Mark M.P.Boneschanscher@uu.nl 10 

Bons, P Pieter P.C.Bons@uu.nl 76 

Castillo, S.I.R. Sonja S.I.R.Castillo@uu.nl 106 

Cats, K.H. Korneel K.H.Cats@uu.nl 32 

Cicmil, D. Dimitrije D.Cicmil@uu.nl 33 

Deka, U. Upakul U.Deka@uu.nl 34 

Dijk, L. van Lourens L.vanDijk@uu.nl 77 

Eilers, J. J. Joren J.J.Eilers@uu.nl 12 

Elbers, N.A. Nina N.A.Elbers@uu.nl 126 

Eschemann, T. O. Thomas T.O.Eschemann@uu.nl 35 

Evers, C.H.J. Chris C.H.J.Evers@uu.nl 108 

Evers, W. H. Wiel W.H.Evers@uu.nl 13 

Folkertsma, E. Emma E.Folkertsma@uu.nl 96 

Folter, J.W.J. de Julius J.W.J.deFolter@uu.nl 109 

Gantapara, A.P. Anjan A.P.Gantapara@uu.nl 128 

Gao, J. Jinbao J.Gao@uu.nl 38 

155

156 

Author Index 


PhD students 

Gatz, H. Henriette H.A.Gatz@uu.nl 78 

Glind, A.J. van de Arjen A.J.vandeGlind@uu.nl 129 

Gosselink, R. W. Rob R.W.Gosselink@uu.nl 41 

Graaf, J. de Joost J.deGraaf1@uu.nl 130 

Grodzinska , D. Dominika D.Grodzinska@uu.nl 14 

Groeneveld, E Esther E.groeneveld@uu.nl 15 

Groot, A. Alexander A.Groot@uu.nl 79 

Haasterecht, T. van Tomas T.vanHaasterecht@uu.nl 43 

Harvey, C.E. Clare C.E.Harvey@uu.nl 43 

Hausoul, P.J.C. Peter P.J.C.Hausoul@uu.nl 44 

Hilhorst, J. Jan J.Hilhorst@uu.nl 110 

Huang, Y. Yuxing Y.Huang@uu.nl 98 

Jastrzebski, R. Robin R.Jastrzebski@uu.nl 46 

Jin, X. Xin X.Jin@uu.nl 80 

Jong, M.M. de Minne M.M.deJong@uu.nl 81 

Jongerius, A.L. Annelie A.L.Jongerius@uu.nl 47 

Jose, J. Jissy J.Jose@uu.nl 131 

Kamp, M. Marlous M.Kamp@uu.nl 132 

Karreman, M.A. Matthia M.A.Karreman@uu.nl 133 

Knaus, H. Helene H.Knaus@uu.nl 134 

Korstanje, T.J. Ties T.J.Korstanje@uu.nl 99 

Kortschot, R.J. Rob R.J.Kortschot@uu.nl 112 

Krumer, Z Zachar Z.Krumer@uu.nl 16 

Kuang, Y. Yinghuan Y.Kuang@uu.nl 82 

Kuijk, A. Anke A.Kuijk@uu.nl 135 

Kurian, R. Reshmi R.Kurian@uu.nl 48 

Kwaadgras, B.W. Bas B.W.Kwaadgras@uu.nl 136 

Landheer, K. Kees C.Landheer@uu.nl 83 

Lange, A. van Arjon A.J.vanLange@uu.nl 84 

Leeuwen, Y.M. van Mikal Y.M.vanLeeuwen@uu.nl 113

Author Index 

Surname, Initials Name c E-mail Page 

PhD students 

Leferink op Reinink, A.B.G.M. Anke A.B.G.M.LeferinkopReinink@uu.nl 114 

Lima Oliveira, R. Rafael R.deLimaOliveira@uu.nl 50 

Linden, M.N. van der Marjolein M.N.vanderLinden@uu.nl 137 

Luo, W. Wenhao W.Luo@uu.nl 51 

Meijer, J. Janne-Mieke J.Meijer1@uu.nl 115 

Miedema, P. S. Piter P.S.Miedema@uu.nl 52 

Milinkovic, K. Kristina K.Milinkovic@uu.nl 139 

Mohan, A. Akshata A.Mohan@uu.nl 86 

Munnik, P. Peter P.Munnik@uu.nl 54 

Mussmann, O. Ole B.O.Mussmann@uu.nl 87 

Ni, R. Ran r.Ni@uu.nl 141 

Nijs, B. de Bart B.deNijs@uu.nl 142 

Otter, den, J.H. Arjan J.H.denOtter@uu.nl 55 

Peng, B. Bo B.Peng@uu.nl 143 

Pietra, F. Francesca F.Pietra@uu.nl 18 

Prastani, C. Caterina C.Prastani@uu.nl 88 

Qian, Q Qingyun Q.Qian@uu.nl 56 

Rabouw, F. T. Freddy F.T.Rabouw@uu.nl 20 

Raju, S. Suresh S.Raju@uu.nl 100 

Rashid, Z. Zahid Z.Rashid@uu.nl 152 

Ravensteijn, B.G.P. van Bas B.G.P.vanRavensteijn@uu.nl 116 

Rijssel, J. van Jos J.vanRijssel@uu.nl 117 

Ristanović, Z Zoran Z.Ristanovic@uu.nl 58 

Rossi, L. Laura L.Rossi@uu.nl 118 

Samarai, M. al Mustafa M.alSamarai@uu.nl 60 

Sattler, J.J.H.B. Jesper J.J.H.B.Sattler@uu.nl 61 

Schooneveld, M. M. van Matti M.M.vanSchooneveld@uu.nl 62 

Schrojenstein Lantman, E.M. Evelien E.M.SchrojensteinLantman@uu.nl 63 

Spannring, P. Peter P.Spannring@uu.nl 101 

Spee, D.A. Diederick D.A.Spee@uu.nl 89 

157

158 

Author Index 


PhD students 

Stellwagen, D. R. Daniel D.R.Stellwagen@uu.nl 65 

Stewart. J.A. Joseph J.A.Stewart@uu.nl 66 

Torres, H. Hirsa H.M.TorresGalvis@uu.nl 68 

Troppenz, T. Thomas T.Troppenz@uu.nl 145 

Veldhuizen, L.W. Pim L.W.Veldhuizen@uu.nl 90 

Vis, M. Mark M.Vis@uu.nl 119 

Voskuilen, C.J. van Johan C.J.vanVoskuilen@uu.nl 148 

Vutukuri, H.R. Hanumantha H.R.Vutukuri@uu.nl 149 

Werkhoven, T.I.M. van Tim T.I.M.vanWerkhoven@uu.nl 150 

Wild, J. de Jessica J.deWild@uu.nl 91 

Winter, D. A. M. de Matthijs D.A.M.deWinter@uu.nl 71 

Wolters, J.R. Joost J.R.Wolters@uu.nl 120 

Yazerski, V.A. Vital V.Yazerski@uu.nl 102 

Zandvoort, I. van Ilona I.vanZandvoort@uu.nl 72 

Zečević, J. Jovana J.Zecevic@uu.nl 73 

Zhang, H. Hao H.Zhang1@uu.nl 92 

Zhao, Y. M. Yiming Y.M.Zhao@uu.nl 22

Author Index 


Postdoctoral researchers 

Agronskaia, A.V. Alexandra A.V.Agronskaia@uu.nl 122 

Ashton, D. Douglas D.J.Ashton@uu.nl 123 

Bossa, C. Christina C.Bossa@uu.nl 30 

Buurmans, I.L.C. Inge I.L.C.Buurmans@uu.nl 31 

Casavola, M. Marianna M.Casavola@uu.nl 11 

Costo Camara, R. Rocio R.CostoCamara@uu.nl 107 

Derrah, E.J. Eric E.J.Derrah@uu.nl 95 

Fan. F. Fengtao F.Fengtao@uu.nl 36 

Fereidouni, F. Farzad F.Fereidouni@uu.nl 127 

Frey, A. M. Anne Mette A.M.Frey@uu.nl 37 

Gatineau, D.M.R.A. David D.M.R.A.Gatineau@uu.nl 97 

Gibson, E.K. Emma E.K.Gibson@uu.nl 39 

Gonzales-Jimenez, I.D. Ines I.D.GonzalesJimenez@uu.nl 40 

Hofmann, J.P. Jan Philipp J.P.Hofmann@uu.nl 45 

Kleshchanok, D Dzina D.Kleshchanok@uu.nl 111 

Lezcano-Gonzalez, I. Ines I.LezcanoGonzales@uu.nl 52 

Liu, B. Bing B.Liu@uu.nl 138 

Martín-Rodríguez, R. Rosa R.MartinRodriguez@uu.nl 17 

Meenakshisundaram, S Sankar M.Sankar@uu.nl 52 

Mint Moustapha, O. Oumkelthoum O.MintMoustapha@uu.nl 85 

Mitoraj, D. Dariusz D.Mitoraj@uu.nl 18 

Nadyarnykh, O. Oleg O.Nadyarnykh1@uu.nl 140 

Prieto, G. Gonzalo G.PrietoGonzalez@uu.nl 56 

Qi, W. Weikai W.Qi@uu.nl 144 

Ruiz-Martinez, J. Javier J.RuizMartinez@uu.nl 59 

Shakeri, M. Mozaffar M.Shakeri@uu.nl 64 

Telalović, S. Selvedin S.Telalovic@uu.nl 67 

Truong, H.H. Hoa H.H.Truong@uu.nl 146 

Vissers T. Teun T.Vissers@uu.nl 147 

159

160 

Author Index 


Postdoctoral researchers 

Vugt, L. K. van (Lam)Bert L.K.VanVugt@uu.nl 21 

Wang, Q. Qingqing Q.Wang1@uu.nl 69 

Wiedemann, S.C.C. Sophie S.C.C.Wiedemann@uu.nl 70

Techniques index 

Computer simulations 

Ab-initio valence bond method Reshmi Kurian 

Band structure calculations Arjon van Lange 


Charge transfer multiplet calculations Reshmi Kurian, Piter S. Miedema, Matti M. van 

Schooneveld 

Complete Active Space SCF method (CASSCF) Zahid Rashid 

Coupled Cluster method (CCSD(T)) Zahid Rashid 

Density functional theory (DFT) Reshmi Kurian, Zahid Rashid, Simone Belli, 

Piter S. Miedema, Matti M. van Schooneveld, Ties 

Korstanje 

Einstein integration Anjan Prasad, Bas Kwaadgras, Kristina 

Milinkovic, Ran Ni, Teun Vissers 

Finite Difference Time Domain (FDTD) modeling Lourens van Dijk 

Large matrix eigenvalue calculations Bas Kwaadgras 

Molecular dynamics simulations Simone Belli, Ran Ni 

Monte Carlo simulations Douglas Ashton, Simone Belli, Anjan Prasad, 

Marjolein van der Linden, Kristina Milinkovic, 

Ran Ni, Weikai Qi, Thomas Troppenz, Teun 

Vissers 

Nematic liquid crystalline theory Thomas Troppenz 

Onsager theory Thomas Troppenz 

Tessellation and interference algorithms Joost de Graaf 

Variable box-shape NPT simulations Douglas Ashton, Anjan Prasad, Joost de Graaf, 

Bas Kwaadgras, Ran Ni, Weikai Qi 

Microscopy 

Atomic force microscopy (AFM) Mark Boneschanscher, Fengtao Fan, Minne de 

Jong, Akshatha Mohan, Hao Zhang 

AFM–Raman Clare Harvey, Jan Philipp Hofmann, Evelien van 

Schrojenstein Lantman 

Confocal fluorescence microscopy Inge Buurmans, Thijs Besseling, Nina Elbers, 

Farzad Fereidouni, Jissy Jose, Marlous Kamp, 

Anke Kuijk, Marjolein van der Linden, Bing Liu, 

Bo Peng, Hanumantha Rao Vutukuri, Qingyun 

Qian, Zoran Ristanović, Jan Hilhorst, Anke 

Leferink op Reinink, Janne-Mieke Meijer, Laura 

Rossi 

161

162 


Microscopy 

Correlative microscopy Alexandra Agronskaia 

Cryo–TEM Bart de Nijs, Jos van Rijssel 

Electron tomography (3D-TEM) Wiel Evers, Roy van den Berg, Bart de Nijs, 

Gonzalo Prieto, Jovana Zečević 

Focussed Ion Beam - Scanning Electron Microscopy Matthijs de Winter 

(FIB-SEM) 

Fluorescence microscopy Lambert van Vugt, Hoa Truong, Oleg 

Nadyarnykh, Johan van Voskuilen, Alexandra 

Agronskaia, Matthia Karreman, Helene Knaus 

High resolution transmission X-ray Mocroscopy Janne-Mieke Meijer 

(HRTXM) 

Integrated laser & electron microscopy (ILEM) Inge Buurmans, Alexandra Agronskaia, Matthia 

Karreman 

Multiphoton excitation microscopy Oleg Nadyarnykh, Hoa Truong, Johan van 

Voskuilen, Tim van Werkhoven, Helene Knaus 

Optical microscopy Nina Elbers, Jissy Jose, Oleg Nadyarnykh, Johan 

van Voskuilen, Hao Zhang, Chris Evers, Julius de 

Folter, Laura Rossi, Mark Vis, Joost Wolters 

Polarization microscopy Anke Leferink op Reinink 

Scanning electron microscopy (SEM) Jinbao Gao, Yuen Au, Marlous Kamp, Bo Peng, 

Hanumantha Rao Vutukuri, Mozaffar Shakeri, 

Yinghuan Kuang, Hao Zhang, Sonja Castillo, 

Mikal van Leeuwen, Bas van Ravensteijn, Laura 

Rossi 

Scanning near-field optical microscopy (SNOM) Arjon van Lange 

Scanning transmission electron microscopy – electron Mustafa al Samarai 

energy loss spectroscopy (STEM-EELS) 

Scanning transmission X-ray microscopy (STXM) Luis Aramburo, Inés González, Korneel Cats, 

Hendrik van der Bij, Mustafa al Samarai, Jesper 

Sattler, Jan Hilhorst 

Scanning tunnelling microscopy/spectroscopy (STM/ Mark Boneschanscher, Farzad Fereidouni 

STS) 

Single molecule fluorescence microscopy Zoran Ristanović

Microscopy 


Transmission electron microscopy (TEM) Wiel Evers, Esther Groeneveld, Yiming Zhao, 

Dilek Boga, Anne Mette Frey, Marianna Casavola, 

Francesca Pietra, Dariusz Mitoraj, Roy van den 

Berg, Korneel Cats, Thomas Eschemann, Rob 

Gosselink, Alexandra Agronskaia, Arjen van de 

Glind, Matthia Karreman, Anke Kuijk, Bing 

Liu, Bo Peng, Peter Munnik, Arjan den Otter, 

Gonzalo Prieto, Selvedin Telalović, Hirsa Torres, 

Jovana Zečević, Akshatha Mohan, Caterina 

Prastani, Pim Veldhuizen, Roel Baars, Susanne van 

Berkum, Sonja Castillo, Rocio Costo, Chris Evers, 

Mikal van Leeuwen, Anke Leferink op Reinink, 

Bas van Ravensteijn, Laura Rossi, Joost Wolters 

Scattering techniques 

Dynamic light scattering (DLS) Chris Evers, Mikal van Leeuwen, Jos van Rijssel, 

Joost Wolters 

Electron backscattered diffraction (EBSD) Matthijs de Winter 

Resonant inelastic X-ray scattering (RIXS) Matti M. van Schooneveld 

Small angle X-ray scattering (SAXS) Dzina Kleshchanok, Anke Leferink op Reinink, 

Janne-Mieke Meijer 

Static light scattering (SLS) Nina Elbers, Jissy Jose, Janne-Mieke Meijer 

Surface enhanced Raman scattering (SERS) Clare Harvey 

Spectroscopy 

Atomic absorption spectroscopy (AAS) Tomas van Haasterecht, Wenhao Luo, Alexander 

Groot 

Attenuated Total Reflectance IR spectroscopy (ATR-IR) Dilek Boga, Wenhao Luo 

Complex magnetic susceptibility spectroscopy Roel Baars 

Dielectric spectroscopy Rob Kortschot 

(in-situ) FTIR Sankar Meenakshisundaram, Sophie Wiedemann, 

Ilona van Zandvoort, Xin Jin, Peter Spannring, 

Susanne van Berkum, Bas van Ravensteijn 

Diffuse Reflectance Infrared Fourier Transform 

Dimitrije Cicmil, Peter Munnik 

spectroscopy (DRIFTS) 

163

164 


Spectroscopy 

Diffuse Reflectance UV-VIS-NIR spectroscopy Dimitrije Cicmil 

Electrical impedance spectroscopy Mark Vis 

Elemental Analysis (ICP) Qingqing Wang 

Energy dispersive X-ray (EDX) spectroscopy Emma Gibson, Caterina Prastani 

Extented X-ray absorption fine structure spectroscopy Dilek Boga, Upakul Deka, Inés D. Gonzalez, 

(EXAFS) 

Sankar Meenakshisundaram, Mustafa al Samarai 

Fourier transform photocurrent spectroscopy (FTPS) Pim Veldhuizen 

IR spectroscopy Upakul Deka, Luis Aramburo, Hendrik van der 

Bij, Qingyun Qian, Zoran Ristanović, Qingqing 

Wang, Diederick Spee, Emma Folkertsma, Suresh 

Raju, Sonja Castillo, Rocio Costo 

Luminescence spectroscopy Joren Eilers, Francesca Pietra, Esther Groeneveld, 

Yiming Zhao, Rosa Martin-Rodriguez, Lambert 

van Vugt, Jessica de Wild 

Microfocus X-ray fluorescence Javier Ruiz-Martínez 

NMR spectroscopy Peter Hausoul, Annelie Jongerius, Hendrik van 

der Bij, Robin Jastrzebski, Ines Lezcano-Gonzales, 

Mozaffar Shakeri, Joseph Stewart, Qingqing 

Wang, Manuel Basauri Molina, Eric J. Derrah, 

David Gatineau, Yuxing Huang, Suresh Raju, Peter 

Spannring, Vital A. Yazerski, Bas van Ravensteijn 

Optical emission spectroscopy (OES) Kees Landheer, Caterina Prastani 

Photothermal deflection spectroscopy (PDS) Caterina Prastani 

Raman spectroscopy Clare Harvey, Emma Gibson, Dimitrije Cicmil, 

Fengtao Fan, Jesper Sattler, Oumkelthoum Mint 

Moustapha 

Reflection/transmission spectroscopy Henriette Gatz 

Single particle spectroscopy Yiming Zhao 

Time resolved laser spectroscopy Esther Groeneveld, Yiming Zhao, Dominika 

Grodzinka, Francesca Pietra, Rosa Martin- 

Rodriguez, Joren Eilers, Jessica de Wild 

Tip-Enhanced Raman Spectroscopy Evelien van Schrojenstein Lantman 

UV-Vis-NIR spectroscopy Dominika Grodzinska, Esther Groeneveld, Rosa 

Martin-Rodriguez, Joren Eilers, Wiel Evers, Arjen 

van de Glind 

UV-Vis spectroscopy Luis Aramburo, Inge Buurmans, Upakul Deka, 

Wiel Evers, Dariusz Mitoraj, Carlo Angelici, 

Hendrik van der Bij, Robin Jastrzebski, Ines 

Lezcano-Gonzalez, Qingyun Qian, Sophie 

Wiedemann

Spectroscopy 


X-ray absorption spectroscopy (XAS) Korneel Cats, Reshmi Kurian, Ines Lezcano- 

Gonzalez, Piter S. Miedema, Javier Ruiz- 

Martínez, Jesper Sattler 

X-ray photoelectron spectroscopy (XPS) Inés González, Rob Gosselink, Piter S. Miedema 

Synthesis methods 

Catalyst Preparation Carlo Angelici 

Cell culture Hoa Truong 

Chemical vapor deposition (CVD) Henriette Gatz, Xin Jin, Minne de Jong, 

Yinghuan Kuang, Kees Landheer, Oumkelthoum 

Mint Moustapha, Akshatha Mohan 

Cluster Deposition Lourens van Dijk 

Colloidal synthesis Marianna Casavola, Wiel Evers, Joren Eilers, 

Anke Kuijk, Bo Peng, Evelien van Schrojenstein 

Lantman, Roel Baars, Sonja Castillo, Rocio Costo, 

Chris Evers, Mikal van Leeuwen, Joost Wolters 

Hot wire CVD (HWCVD) Henriette Gatz, Xin Jin, Yinghuan Kuang, 

Diederick Spee, Pim Veldhuizen 

iCVD Diederick Spee 

Inorganic synthesis Christina Bossa, Roy van den Berg, Gonzalo 

Prieto, Daniel Stellwagen 

Nanoparticle synthesis Bart de Nijs, Björn Ole Mußmann 

Organic synthesis Daniel Stellwagen, David Gatineau, Yuxing 

Huang, Vital A. Yazerski 

Organometallic synthesis Peter Hausoul, Lambert van Vugt, Manuel Basauri 

Molina, Eric J. Derrah, Emma Folkertsma, David 

Gatineau, Ties Korstanje 

Very high frequency plasma enhanced CVD (VHF Henriette Gatz, Xin Jin, Minne de Jong, 

PECVD) 

Yinghuan Kuang, Kees Landheer, Oumkelthoum 

Mint Moustapha, Akshatha Mohan, Pim 

Veldhuizen, 

165

166 


Techniques (general) 

Adaptive Optics Tim van Werkhoven 

Alternating gradient magnetometry (AGM) Susanne van Berkum, Jos van Rijssel 

Analytical centrifugation Rocio Costo 

Catalytic testing Roy van den Berg, Annelie Jongerius, Thomas 

Eschemann, Robin Jastrzebski, Sankar 

Meenakshisundaram, Gonzalo Prieto, Hirsa 

Torres, Ilona van Zandvoort, Ties Korstanje 

Chemical Imaging Fengtao Fan, Emma Gibson 

Chemisorption Anne Mette Frey, Tomas van Haasterecht, Arjan 

den Otter 

Conductivity measurements Nina Elbers, Henriette Gatz, Xin Jin, 

Oumkelthoum Mint Moustapha 

Differential scanning calorimetry (DSC) Christina Bossa, Arjen van de Glind 

Electroacoustics Rob Kortschot 

Electrochemical potential measurements Mark Vis 

Electrospray ionization (ESI) MS Manuel Basauri Molina, Eric J. Derrah, Emma 

Folkertsma, Yuxing Huang, Suresh Raju, Peter 

Spannring 

Emulsification Bart de Nijs 

Focused Ion Beam (lithography) Lambert van Vugt, Jan Hilhorst 

Gas chromatography (GC) Carlo Angelici, Rob Gosselink, Tomas van 

Haasterecht, Jesper Sattler, Daniel Stellwagen, 

Joseph Stewart, Selvedin Telalović, Hirsa Torres, 

Ilona van Zandvoort, Ties Korstanje, Peter 

Spannring, Vital A. Yazerski 

Gas chromatography-mass spectrometry (GC-MS) Annelie Jongerius, Wenhao Luo, Robin 

Jastrzebski, Yuxing Huang, Suresh Raju 

Gel permeation chromatography (GPC) Annelie Jongerius, Qingqing Wang, Diederick 

Spee 

High performance liquid chromatography (HPLC) Tomas van Haasterecht, Peter Hausoul, Ilona van 

Zandvoort, David Gatineau 

High Precision Parallel Plate Oscillating Shear Cell Thijs Besseling 

(HIPPOS) 

Homogeneous catalysis Manuel Basauri Molina, Emma Folkertsma, Vital 

A. Yazerski 

Interfacial tension measurement Julius de Folter, Mark Vis 

Laser cooling Pieter Bons, Alexander Groot, Arjon van Lange, 

Björn Ole Mußmann 

Laser Doppler electrophoresis Rob Kortschot, Jos van Rijssel

Techniques (general) 

Liquid chromatography (LC) Joseph Stewart 

Magnetic traps Pieter Bons, Alexander Groot 


Mass spectrometry (MS) Upakul Deka, Minne de Jong, Akshatha Mohan 

Microtomy Peter Munnik 

N -physisorption 2 Jinbao Gao, Christina Bossa, Carlo Angelici, 

Yuen Au, Rafael Lima Oliveira, Arjan den Otter, 

Mozaffar Shakeri, Selvedin Telalović, Jovana 

Zečević 

Optical tweezers Pieter Bons, Alexander Groot, Arjon van Lange 

Particle Tracking Thijs Besseling 

Quasi-steady state photoconductance Kees Landheer 

Retarding-field ion energy analysis Minne de Jong 

Rheology/reometry Dzina Kleshchanok 

Solar simulator Jessica de Wild 

Spin dependent photoconductivity (SDPC) Kees Landheer 

Temperature programmed desorption/reduction (TPD/ Jinbao Gao, Anne Mette Frey, Wenhao Luo, Yuen 

TPR) 

Au, Thomas Eschemann, Rob Gosselink 

Thermogravimetric analysis (TGA) Arjen van de Glind, Mozaffar Shakeri, Sophie 

Wiedemann 

Ultrafast pump-probe Dariusz Mitoraj 

Wavefront Sensing Tim van Werkhoven 

X-ray crystallography Peter Hausoul, Eric J. Derrah 

X-ray diffraction tomography Javier Ruiz-Martínez 

X-ray powder diffraction (XRD) Anne Mette Frey, Dilek Boga, Jinbao Gao, Inés 

González, Yuen Au, Rafael Lima Oliveira, Ines 

Lezcano Gonzalez, Daniel Stellwagen, Joseph 

Stewart, Selvedin Telalović, Hirsa Torres, Jovana 

Zečević, Yinghuan Kuang 

167

168 

Techniques Index

Debye Institute for Nanomaterials Science

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?