Berlin 2005 – scientific programme

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MO: Molekülphysik

MO 22: Poster I

MO 22.14: Poster

Saturday, March 5, 2005, 10:30–12:30, Poster HU

Infrared Photodissociation Spectroscopy of Gas-Phase Mass-Selected Vanadium Oxide Cluster Anions — •Gabriele Santambrogio¹, Mathias Brümmer¹, Joachim Sauer², Ludger Wöste¹ und Knut Asmis³ — ¹Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin — ²Institut für Chemie, Humboldt-Universität Berlin, Unter den Linden 6, 10099, Berlin — ³Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Molekülphysik, Faradayweg 4-6, 14195, Berlin

Infrared photodissociation spectroscopy is one of the few methods available to investigate the structure of selected clusters in the gas-phase. Here we present the first infrared spectra of gas-phase mass-selected vanadium oxide cluster anions in the spectral region from 6 to 16 microns. Anions were produced by laser vaporization and excited using tunable infrared radiation from a free electron laser (FELIX, at the FOM Institute for Plasma Physics in Nieuwegein, NL). We investigated clusters from V₂O₆⁻ up to V₈O₂₀⁻. By comparison with DFT calculations we were able to unambiguously determine the structure of the clusters. The structures of the small anions are similar, though not identical, to those already observed for the cationic species, consisting of a planar central V-O-V-O ring. For larger anions we observed for the first time the predicted highly symmetric cage structures. Furthermore, we found a size-dependent charge localization in polyhedral cage structures of (V₂O₅)_n clusters (n=2,3,4).