HIGHLY PREDISSOCIATIVE LEVELS OF THE $CH_{3}S A^{2}A_{1}$ STATE DETERMINED WITH DEGENERATE FOURWAVE MIXING
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Date
2002
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Ohio State University
Abstract
We have determined highly predissociative levels of the $A^{2}A_{1}$ state of $CH_{3}S$ in a supersonic jet with degenerate fourwave mixing (DFWM) technique. The highest level observed lies $4265 cm^{-1}$ above the zero-point-energy level, much greater than corresponding values of $2979 cm^{-1}$ observed by fluorescence depletion spectroscopy and $1490 cm^{-1}$ by laser-induced fluorescence. Unlike in fluorescence spectra, relative intensities of lines in DFWM spectra closely reflect their Franck-Condon factors; vibronic assignments are thus more straightforward. A new progression involving excitation of the $CH_{3}$ stretching mode is identified, and several lines in the range $1290-1410 cm^{-1}$ above the origin may be assigned to the $CH_{3}$ deformation ($\nu_{5}$) and the first overtone of $CH_{3}$ rocking ($2\nu_{6}$) modes. Observed vibrational wave numbers are consistent with theoretical predictions.
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Author Institution: Department of Chemistry, National Tsing Hua University