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MO: Molekülphysik

MO 1: Posters Monday: Clusters, Fullerenes and Nanotubes

MO 1.20: Poster

Montag, 2. April 2001, 12:30–15:00, AT3

Laser depletion during gold cluster anion reactions in an octopole ion trap — •Maryam Elijazyfer¹, 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

Small supported gold clusters have been found to efficiently catalyze the oxidation of carbon monoxide even at cryogenic temperatures [1]. The presented investigations aim to model this catalytic activity of gold particles with very small gas phase clusters. The clusters are produced in a sputtering ion source (CORDIS), mass selected in a quadrupole mass spectrometer and transferred into a variable temperature octopole ion trap. This octopole trap contains a gas mixture of helium, oxygen and carbon monoxide. The ionic reaction products are finally measured as a function of storage time by using a second quadrupole mass spectrometer. We find that at temperatures below 250 K already gold dimer and trimer anions show reaction products containing both, O₂ and CO adsorbates. In order to further characterize the structure of the adsorbate complexes, we perform laser depletion spectroscopy and monitor the product concentrations as a function of reaction time and laser wavelength. [1] M. Haruta, Catalysis Today, 36, 153-166, 1997