Book of Abstracts Book of Abstracts - Universität Konstanz

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Interaction of oxygen with mass-selected Ag cluster anions and nanoparticles Ignacio Lopez-Salido, Dong Chan Lim, Gerd Ganteför, and Young Dok Kim Department of Physics, University of Konstanz, D-78457 Konstanz, Germany http://www.clusterphysik.uni-konstanz.de/ B - 23 Adsorption of oxygen on free negatively charged Ag clusters were studied using Time-of- Flight mass spectrometry and photoelectron spectroscopy. In contrast to the results of Au cluster anions, which become inert towards oxygen chemisorption for Au n - with n > 20, Ag clusters consisting of more than 30 atoms are still reactive towards O 2 chemisorption. The even-odd alteration of the O 2 chemisorption reactivity was found, which has been also observed for the Au cluster anions. Photoelectron spectroscopy was used to study the nature of oxygen species on the Ag cluster anions. To shed light on the chemical properties of larger Ag nanoparticles, we deposited Ag on Highly Ordered Pyrolytic Graphite (HOPG) surfaces, leading to the formation of Ag nanoparticles with particle diameters up to 10 nm. Scanning Tunneling Microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS) results suggest quite narrow size distributions of Ag islands on HOPG, allowing investigations on size dependent changes of electronic and chemical properties of Ag nanoparticles. For the Ag nanoparticles smaller than 10 nm, completely different oxidation patterns were observed compared to the Ag bulk crystal. We found Ag oxide species, which cannot be observed by oxidation of Ag bulk crystal. Implication of this result in heterogeneous catalysis is discussed in connection with the size selectivity in ethylene epoxidation. 61
B - 24 62 Joint theoretical and experimental investigations of reactivity of anionic and cationic gold oxide clusters with carbon monoxide Christian Bürgel 1 , Roland Mitrić 1 , Vlasta Bonačić-Koutecký 1 , Michele L. Kimble 2 , Nelly A. Moore 2 , A. Welford Castleman Jr. 2 1 Humboldt Universität zu Berlin, Institut für Chemie, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany 2 Department of Chemistry and Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA Recent literature shows that gold oxides, containing both atomic and molecular oxygen may play a role as the active site in supported gold catalysts. Therefore, a fundamental question can be raised as to whether it is sufficient to have an atomic oxygen in order for the oxidation reaction to proceed. A second fundamental question concerns the role of a charge. We will address both aspects by presenting the oxidation of CO in the presence of anionic and cationic gas phase gold oxide clusters. The influence of the charge on the association and replacement reaction has been also investigated. The experimental studies were carried out utilizing a metal ion flow tube in conjunction with a guided ion beam apparatus where gold oxides with both atomized and molecular oxygen are produced. Based on DFT and CCSD calculations we identified the reactive center and proposed reaction mechanisms. It will be shown that a peripheral O-atom is the most effective center for the oxidation reaction, while cooperative effects are mandatory for a reaction to proceed if molecular oxygen is involved. However, the presence of atomic oxygen does not guarantee that the oxidation reaction will proceed. We also wish to show the importance of cationic clusters for the association and replacement reactions. References [1] M. L. Kimble, A. W. Castleman, Jr., R. Mitrić, C. Bürgel, V. Bonačić-Koutecký, J. Am. Chem. Soc., 126, 2526 (2004). [2] M. L. Kimble, C. Bürgel, Nelly A. Moore A. W. Castleman, Jr., R. Mitrić, V. Bonačić-Koutecký, J. Am. Chem. Soc., in prep.
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: B - 22 60 Probing the Electronic St
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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