Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 12: Nanostrukturen I
O 12.2: Vortrag
Freitag, 4. März 2005, 16:00–16:15, TU EB202
Alloy formation of supported Gold nanoparticles at their transition from clusters to solids: Does size matter? — •H.-G. Boyen1, A. Ethirajan1, G. Kästle1, F. Weigl1, P. Ziemann1, G. Schmid2, M.G. Garnier3, M. Büttner3 und P. Oelhafen3 — 1Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm — 2Institut für Anorganische Chemie, Universität Duisburg-Essen, Universitätsstrasse 5-7, D-45117 Essen — 3Institut für Physik, Universität Basel, Klingelbergstr. 82, CH-4056 Basel
Gold nanoclusters of a size approaching the molecular limit (<3nm) were prepared on Si substrates in order to study alloy formation on the nanometer scale. For this purpose, Indium atoms are deposited on top of the gold particles at room temperature and the formation of AuIn2 is studied by X-ray Photoelectron Spectroscopy (XPS) in situ. It is observed that the alloy formation takes place independent of whether the particles electronically are in an insulating molecular or in a metallic state. Most important, however, closed packed full-shell clusters containing 55 Au atoms are found to exhibit an outstanding stability against alloying despite a large negative heat of formation of the bulk Au-In system. Thus, Au55 clusters may play a significant role for the design of nanoscaled devices where chemical inertness is of crucial importance.