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Melting, Pre-melting, and Glass Transitions in Gallium and Aluminum Clusters G.A. Breaux, B. Cao, C.M. Neal, and M. F. Jarrold Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405- 7102, USA The melting of gallium and aluminum clusters with between 10 and 70 atoms has been examined using multicollision induced dissociation (MCID) calorimetry measurements and high temperature ion mobility measurements. A first order melting transition is indicated by a spike in the heat capacity due to the latent heat and an abrupt change in the average collision cross section due to a change in the volume or shape of the cluster when it melts. For some aluminum clusters (e.g. Al51 + and Al52 + ) the peaks in the heat capacity are bimodal suggesting the presence of a pre-melting transition where the surface of the cluster melts before the core. While premelting transitions are present in many simulations of cluster melting, this is the first time they have been observed experimentally. For some gallium clusters, the collision cross sections suggest that a melting transition occurs while there is no peak in the heat capacity. This is the signature for a glass transition which has been predicted to occur for some cluster sizes in several recent simulations. A glass transition occurs for clusters which are intrinsically amorphous - clusters that do not have a well-defined geometry. 27
Phase Transition and Phase Coexistence in Atomic Clusters and Other Mesoscopic Systems 28 Mihai Horoi, Koblar Alan Jackson Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USA We investigate signatures of shape transition and shape coexistence phases in small atomic clusters and other mesoscopic systems, such as the atomic nuclei. One of the best know example is the prolate-compact shape transition/coexistence phenomena observed in the mobility experiments of Si clusters.[2] Using a hierarchical strategy that features an extensive tightbinding-based search of the energy surface, followed by a full density functional theory investigation of the most stable structures, we have determined the lowest-energy clusters across the range n=2 to 28.[3] The calculated properties of these clusters are in very good agreement with available measurements of dissociation energies, ionization energies and ion mobilities, providing strong evidence that these structures are the ones found in experiments. The calculations clearly exhibit a transition in the relative stability of prolate and compact clusters between n=25 and 26, coinciding exactly with the experimental behavior. The lowest energy prolate and compact structures are found almost degenerate, justifying the coexistence of shapes observed in the experiment. The binding energy per atom of the ground states vs N -1/3 exhibits a long plateau in the transition/coexistence region (see Fig.), suggesting that this phenomena may be related to a relative soft surface tension. Similar behavior was recently found in the isotope 152 of the nucleus of the element Sm, for which the ground sate, J π = 0 + , is known to be very deformed (oblate), and the first excited J π = 0 + , is compact. A similar signature in the binding energy per atom of the Sm isotopes can also be extracted from the available experimental data. Figure 1. Shape transition and shape coexistence signature in the binding energy per atom of Si clusters. Figure taken from Ref. [1], but red dots are the results of our simulations (Ref. [3]). References [1] T. Bachels and R. Schaefer, Chem. Phys. Lett. 324, 356 (2000). [2] R.R. Hudgins, I. Motoharu, and M.F. Jarrold, J. Chem. Phys. 111, 7865 (1999). [3] A.K. Jackson, M. Horoi, I. Chaudhuri, Th. Fraunheim, and A. A. Shvartsburg, Phys. Rev. Lett. 93, 013401 (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 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 128 and 129:
Structural changes in small and med
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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