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MO: Molekülphysik

MO 17: Poster II

MO 17.18: Poster

Thursday, March 25, 2004, 14:00–16:00, Schellingstr. 3

Infrared spectroscopy of gas phase cluster anions — •J. Mathias Weber, Holger Schneider, and Alexia Glöß — Institut für Physikalische Chemie, Universität Karlsruhe, D-76128 Karlsruhe, Deutschland

Ion-molecule complexes of atomic anions with carbon dioxide have been studied by gas phase infrared photodissociation spectroscopy. Ions were formed by attachment of secondary electrons to atomic and molecular precursors in the electron impact plasma generated in the high density region of a pulsed supersonic expansion. Ions were mass selected using a time-of-flight mass spectrometer, and interacted with pulsed infrared radiation from an optical parametric oscillator/amplifier. Spectra were taken between 2250 cm⁻¹ and 3800 cm⁻¹ by monitoring the fragment ions generated by vibrational predissociation, and interpreted using quantum chemical calculations. We observe that for clusters containing halide anions, the asymmetric stretch mode of the carbon dioxide molecule is red shifted from the frequency of free carbon dioxide, with the red shift increasing towards the lighter halide ions.