15min:

J. B. JAEGER, T. D. JAEGER AND M. A. DUNCAN, University of Georgia, Department of Chemistry, Athens, GA, 30602-2556.

Weakly bound Si⁺(CO₂)_n, Si⁺(CO₂)_nAr, and Si⁺(O₂)(CO₂)_n complexes are produced by laser vaporization in a pulsed supersonic expansion. The ions are then mass selected in a reflectron time-of-flight mass spectrometer where they are photodissociated by a tunable infrared OPO/OPA laser system near the asymmetric stretch ( ₃) of CO₂. Dissociation is more efficient on resonance, thus monitoring the fragmentation channel as a function of infrared laser frequency produces the IR absorption spectrum for the complex of interest. Si⁺(CO₂)_n and Si⁺(O₂)(CO₂)_n clusters fragment by the loss of whole CO₂ units while Si⁺(CO₂)_nAr complexes fragment by the loss of argon. Interpretation of the observed infrared spectra will be discussed.