Berlin 2005 – scientific programme

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MO: Molekülphysik

MO 14: Clusters of Atoms and Small Molecules

MO 14.7: Talk

Friday, March 4, 2005, 18:15–18:30, HU 2091

Infrared Spectroscopy of Cluster Anions — •J. Mathias Weber, Holger Schneider, and A. Daniel Boese — Institut für Physikalische Chemie, Universität Karlsruhe, Kaiserstr. 12, 76128 Karlsruhe

Molecular clusters are relevant model systems for the study of intermolecular interaction potentials governing the structures of molecular complexes. Structural information on clusters can be gained from infrared photodissociation spectroscopy in molecular beams, and we have applied this technique to several species, probing the interaction of various anions with CO₂. The experimental results are interpreted in the framework of density functional theory calculations with anharmonic calculations of vibrational spectra.

Halide-CO₂ complexes afford the study of the interaction CO₂ with closed shell anions of low reactivity. The results are compared with those for Au⁻ · CO₂, which is relevant for the study of catalytic oxidation of CO. This complex shows strong interaction between CO₂ and the Au⁻ anion, with a strongly deformed CO₂ unit. Complexes of O₂⁻ with CO₂ show very intersting motifs of ion solvation. The π^* orbital offers a template with four a priori equivalent binding sites for the structure of the microsolvation environment. However, only one CO₂ ligand is strong bound, with additional molecules weakly attached to the resulting CO₄⁻ anion.