Knowledge Bank

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 $(\nu 3)$ 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.