Physik: DPG Tagungen - Sitzung O 28 - Nano-science.de

Physik: DPG Tagungen - Sitzung O 28
http://www.dpg-tagungen.de/archive/2004/o_28.html
Bildkontrast empfindlich von der ausgewählten Energie der Elektronen abhängt. Die derzeitige Begrenzung der
räumlichen (160nm) und zeitlichen Auflösung der Methode ist durch die Repetitionsrate (1kHz) des anregenden
Lasers bedingt.
O 28.35 Poster Mi 16:00 Bereich C
Growth of Platin Nanowire Networks on Nafion
•M. Elbahri, J. Franc, O.C. Aktas, R. Adelung und F. Faupel
Lehrstuhl für Materialverbunde, Technische Fakultät der CAU Kiel
The Nafion polymer, produced by the Dupont company, is still the most prominent membrane material for the
commercial polymer electrolyte fuel cell (PMFC). Usually, the Nafion membrane is sandwiched by two catalytic
layers, consisting of a metal-Nafion-carbon mixture in order to provide catalytic activity as well as electrical and
proton conductivity. It turns out that most of the Platinum doesn't contribute to the catalytic efficiency, which
increases the total cost for the PMFC-fuel cell. An alternative approach might be a catalytic layer formed by a
Pt-nanowire network. We present here a strategy to deposit Pt in the form of a nanowire networks. Therefore
we used sputter deposited Pt on a vacuum deposited amorphous carbon mask layer. We show different
Pt-nanowire networks generated on the Nafion surface and discuss the mechanisms that tune the network
parameters like nanowire dimensions and mesh width.
The authors thank the Technologiestiftung Schleswig-Holstein for supporting the project.
O 28.36 Poster Mi 16:00 Bereich C
Imaging of optical near fields of nanostructures with fs laser pulses
•Juliane Birk, Johannes Boneberg und Paul Leiderer
Universität Konstanz, FB Physik, LS Leiderer, SFB 513, 78457 Konstanz
The optical properties of nanostructures are a topic of interesting investigations. In analogy to the near fields
around a Hertz dipole we expect near fields in the surrounding of all nanostructures. Up to now they were
analysed with the scanning near field optical microscope (SNOM). We want to introduce an alternative method
to image near fields with intensive short laser pulses. The intensity is adjusted to values where the substrate far
from the particle is not affected. Nevertheless, the surface around and below the particle can be ablated, due to
the local intensity enhancement in the optical near field. After the laser pulse the modified surface is imaged with
atomic force microscopy (AFM) and thus the optical near fields of different nanostructures on several
substrates, for example silicon, can be studied. A few examples of the near fields of various nanostructures are
shown.
O 28.37 Poster Mi 16:00 Bereich C
Infrared-optical properties of Cu nanoparticles on CaF 2 (111)
•Birgit Gehring, Andreas Priebe und Annemarie Pucci
Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, D - 69120 Heidelberg
Using IR spectroscopy the growth of Cu nanoparticles on UHV-cleaved CaF 2 (111) was investigated in situ.
Relative transmission spectra informed about the dynamic conductivity of the nanoparticle film and about the
influence of the substrate temperature on the percolation threshold.
In the range from about 1000 cm -1 up to about 2500 cm -1 a relative transmission > 100 % was observed for Cu
coverage below percolation, which corresponds to an anti-reflection effect. The magnitude of this effect
depends on the growth temperature.
For certain average Cu thicknesses we exposed CO at a sample temperature of about 100 K. The CO adsorption
on different Cu facets was studied by IR transmission spectroscopy. The morphology of the nanoparticle layer
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