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Structural changes in small and medium-size rare-gas cluster cations. Aleš Vítek, František Karlický, and René Kalus Department of Physics, University of Ostrava,30. dubna 22, 701 03 Ostrava, Czech Republic A - 16 Constant-energy and constant-temperature Monte Carlo simulations have been performed to localize temperature-dependent structural changes in selected krypton cluster cations, Kr3 + , Kr4 + , and Kr12-14 + . The trimer and tetramer cations are used to analyze possible structural changes in the ionic cores of larger KrN + clusters, the Kr12-14 + cations are included as representatives of these larger clusters to assess the role of solvation effects and to study the phase changes occurring in neutral solvation shells. The intra-cluster interactions of KrN + are described by means of previously developed models based on the diatomics-in-molecules approach with the inclusion of the spin-orbit coupling and the most important three-body polarization interactions. 123
A - 17 124 Experimental study of the phase transformations in molecular clusters of Ar and N2 O. G. Danylchenko, S. I. Kovalenko, V. N. Samovarov B. Verkin Institute for Low Temperature Physics and Engineering, Natl. Academy of Sciences of Ukraine, 47 Lenin Ave., Kharkov, 61103, Ukraine We use an electron diffraction technique to study the structure of substrate-free Ar and N2 clusters and nanoparticles formed in the process of homogeneous nucleation in a supersonic jet isentropically expanding into vacuum. The average size N of aggregations varied between 5⋅10 2 and 1.5⋅10 5 atoms (molecules) per cluster. The temperature of clusters and nanoparticles was T=(38±5) K in the diffraction zone. Analysis of the obtained electron-diffraction patterns has shown for the first time the existence of an amorphous phase in large rare-gas clusters (N≈600 atoms/cluster). As N increased in a relatively narrow size interval a transition occurred from the amorphous phase to the multilayer icosahedral one observed for N=1300 atoms/cluster. Formation of a crystalline face-centered cubic (fcc) structure of argon with stacking faults took place for N=3⋅10 3 atoms/cluster which is in good accordance with the previous observations [1,2]. The electron-diffraction patterns of bigger clusters (N∼10 4 atoms/cluster) are shown to be characterized by hexagonal close-packed (hcp) maxima along with the fcc peaks. The intensity of the hcp peaks grew with increasing aggregation size, and for nanoparticles with N∼10 5 atoms/cluster we clearly detected (100), (101), (103), and (202) peaks characteristic of an hcp structure with intensity comparable with that of the fcc peaks. In case of linear molecules like those of nitrogen, besides the central interaction between particles there is a considerable contribution of non-central electrostatic forces which are responsible for the orientational ordering of molecules at low temperatures. The structure of such clusters can differ significantly from the structure of rare-gas clusters depending on the anisotropic contribution to the total lattice energy. In contrast to amorphous argon clusters, for nitrogen beams with N≈500 molecules/cluster we first observed the formation of aggregations with multilayer icosahedral packing of molecules. The ‘wings’ of the most prominent icosahedral-phase maximum (in the region corresponding to the (100) and (101) peaks of the high-temperature β phase of N2, α-β phase transition in a bulk at T=35.6 K) are found to be curved thus indicating the presence of traces of the β phase in these clusters. As the cluster size grows at the same T in the diffraction zone, the diffraction pattern undergoes transformations and for N∼10 3 molecules/cluster it contains maxima of both cubic (α) and hcp (β) phases. Further cluster growing is accompanied by a decrease in the intensity of the cubic-phase peaks and strenghening of the hcp peaks. Clusters with N∼10 4 actually have only the high-temperature β phase. We propose and discuss a mechanism underlying the observed structural transformations in Ar and N2 which supposes cluster formation from a liquid droplet and takes into account the kinetics of phase growth when there are energy barriers between phases. References [1] I. Farges, M.F. de Feraudy, B. Roult, G. Torchet, Adv. Chem. Phys. 70, 45 (1988). [2] O.G. Danylchenko, S.I. Kovalenko, V.N. Samovarov, Low Temp. Phys. 30, 166 (2004).
Page 1 and 2:
Symposium on Size Selected Clusters
Page 4:
Table of Contents FULL LENGTH TALKS
Page 8 and 9:
Metallic clusters and oxygen Cather
Page 10 and 11:
Infrared Spectroscopy of Metal Ion
Page 12 and 13:
Model Gold Catalysts by Size-Select
Page 14 and 15:
Ultra-stable Hetero-nuclear Microcl
Page 16 and 17:
Tailoring functionality of clusters
Page 18 and 19:
The hydrogen transfer reaction: fro
Page 20 and 21:
Atomic and Molecular Architecture a
Page 22 and 23:
Magnetic Properties of Deposited Tr
Page 24 and 25:
Cluster ferroelectricity Walt de He
Page 26 and 27:
Oxidation Effects of the Small Chro
Page 28 and 29:
Electronic structure and bonding in
Page 30 and 31:
Catalytic CO oxidation on ionic pla
Page 32 and 33:
Melting, Pre-melting, and Glass Tra
Page 34 and 35:
Vibrational Spectroscopy of Large S
Page 36 and 37:
Novel Properties of Soft-Nano-Molec
Page 38:
Posters 33
Page 42 and 43:
Structure and Bonding in Carbon Clu
Page 44 and 45:
Photoelectron Spectroscopy of Fulle
Page 46 and 47:
Nucleation of single-walled carbon
Page 48:
Chemistry 43
Page 51 and 52:
46 B - 8 Triplatinum carbonyl compl
Page 53 and 54:
B - 10 48 Structural and Electronic
Page 55 and 56:
B - 12 50 Size Dependent Carbon Mon
Page 57 and 58:
B - 14 52 Binding energies of CO an
Page 59 and 60:
B - 16 54 Reactivity of Size-Select
Page 61 and 62:
B - 18 56 Oxygen adsorption at anio
Page 63 and 64:
B - 20 Gold Clusters, CO-Chemisorbe
Page 65 and 66:
B - 22 60 Probing the Electronic St
Page 67 and 68:
B - 24 62 Joint theoretical and exp
Page 70 and 71:
Photoionization Dynamics of Pure He
Page 72 and 73:
Fast Electronic Relaxation in Metal
Page 74 and 75:
Femtosecond photoelectron spectrosc
Page 76 and 77:
Signatures of the Giant Dipole Reso
Page 78 and 79: Embedding of Na clusters in raregas
Page 80 and 81: Theoretical studies of ultrafast pr
Page 82: Magnetism 77
Page 85 and 86: B - 38 80 Mn clusters: a nanoscale
Page 88 and 89: Materials 83
Page 90 and 91: Intensity 10000 8000 6000 4000 2000
Page 92 and 93: Passivation, charging and optical p
Page 94: WS and MoS: Magic Clusters and Nano
Page 98 and 99: PEACE - a new photoelectron action
Page 100 and 101: B - 47 Computational Electron Spect
Page 102 and 103: Photoionisation using Kohn-Sham wav
Page 104: Structural characterization of larg
Page 107 and 108: A - 0 102
Page 109 and 110: A - 2 104 Gold Clusters with Densit
Page 111 and 112: A - 4 Structure Determination of Sm
Page 113 and 114: A - 6 108 Mass Spectrometric Invest
Page 115 and 116: A - 8 110 Probing the properties of
Page 117 and 118: A - 10 112 Planar Boron Clusters an
Page 119 and 120: A - 10 114
Page 121 and 122: A - 12 116 Infrared Spectroscopy of
Page 123 and 124: A - 14 118 Computational Study of (
Page 126 and 127: Phase Transitions 121
Page 130 and 131: Molecular Dynamics Simulations of t
Page 132 and 133: Rare Gases 127
Page 134 and 135: A - 20 Decay behaviour of dimer ion
Page 136 and 137: High resolution electron ionization
Page 138: Photodissociation of rare-gas trime
Page 141 and 142: A - 24 136
Page 143 and 144: A - 26 138 Sizedependence of Electr
Page 146 and 147: Solvations 141
Page 148 and 149: Ionization Potentials of Large Sodi
Page 150: First principles studies on the rea
Page 153 and 154: 148
Page 155 and 156: A - 32 150 Single Atom Dispersion o
Page 157 and 158: A - 34 152 Supported Gold Clusters
Page 159 and 160: A - 36 The Size-Evolution of the Op
Page 161 and 162: A - 38 156 Transition From One- to
Page 163 and 164: A - 40 158 Multiple Size-Selected C
Page 165 and 166: A - 42 160 A comparative simulation
Page 167 and 168: A - 44 DFT-Investigations of coales
Page 169 and 170: A - 46 164 Mass-selected Nanocrysta
Page 172 and 173: Author Index 167
Page 174 and 175: Abbet, S...........................
Page 176 and 177: Murakami, J........................
Page 178:
Time 8.30 a.m. 9.15 a.m. 10.00 a.m.
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Book of Abstracts Book of Abstracts - Universität Konstanz

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