Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Symposium: Bimetallic Nanosystems: Tuning Physical and Chemical Properties II (Invited Speakers: André Fielicke, Thomas Risse, Jürgen Behm)
O 73.5: Vortrag
Donnerstag, 28. Februar 2008, 15:45–16:00, MA 005
Structural fluxionality in the CO adsorption on pure and binary silver-gold clusters AgnAum+ — •Denisia M. Popolan and Thorsten M. Bernhardt — Institut für Oberflächenchemie und Katalyse, Albert-Einstein-Allee 47, Universität Ulm, 89069 Ulm, Germany
Temperature dependent reactivity measurements performed in a low energy ion beam apparatus, consisting of a sputter cluster ion source and a temperature variable octopole ion trap combined with an tandem mass spectrometers arrangement, shed new light on the reactive behaviour of pure and binary silver-gold cluster cations with CO. Several trends in the size and composition dependent reactivity were observed. While all investigated clusters form carbonyl products, the formation kinetics and maximum number of adsorbed CO strongly vary for the different cluster ions. In the case of the trimers, the largest saturation coverage is observed for Au3+. In contrast, for the pentamer clusters the maximum number of adsorbed CO molecules, at low temperatures, increases with increasing number of silver atoms n in AgnAum+ , correlated with a decrease in the CO binding energy. The results are discussed in terms of enhanced structural fluxionality due to the larger silver content in combination with a gradual change in the bonding type of CO to the metal clusters.