Berlin 2001 – scientific programme
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A: Atomphysik
A 4: Clusters I: Metal Clusters (joint session A and MO)
A 4.5: Talk
Monday, April 2, 2001, 16:45–17:00, H1012
Temperature dependent reactions of small gold clusters with oxygen and carbon monoxide — •Liana D. Socaciu1, Jan Hagen1, Ueli Heiz2, Thorsten M. Bernhardt1, and Ludger Wöste1 — 1Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, D-14195 Berlin, Germany — 2Ecole Polytechnique Federale de Lausanne, Institut de Physique Experimentale, CH-1015 Lausanne, Switzerland
While bulk gold material is chemically inert towards O2 and CO, gold nanoparticles exhibit remarkable catalytic properties in the CO oxidation [1]. Recently, it was shown that the charge transfer between the oxide support and the adsorbate is essential for the catalytic activity of gold clusters [2]. From this point of view it is important to make a comparative study of the chemical properties of supported and gas phase clusters. We investigate the reactivity of charged, small, mass-selected Au clusters with O2 and CO in a temperature variable octopole ion trap. Interestingly, Au2− adsorbs only one molecule O2 whereas Au1− and Au3− show no evidence for oxidation. In contrast to the O2 reactions, Au2− and Au3− are able to bind two CO molecules. The measured reaction rates at different temperatures are explained with the electronic stability of the cluster complexes as well as with the metal cluster degrees of freedom involved in the cooling process at lower temperature. [1] M. Haruta, Catalysis Today, 36, 153-166, 1997. [2] A. Sanchez, S. Abbet, U. Heiz, W.-D. Schneider, H. Häkkinen, R. N. Barnett, and Uzi Landman, J. Phys. Chem. A, 103, 9573-9578, 1999.