15min:

C. MUKARAKATE, C. TAO AND S. A. REID, Department of Chemistry, Marquette University, Milwaukee, WI 53233.

Low resolution single vibronic level (SVL) emission spectra of chlorocarbene, CHCl, obtained by Chang and co-workers reveal weak transitions that have been assigned to triplet levels on the basis of high level ab~initio calculations. We recently used K_a-sorted emission spectra to show that the A rotational constant of the presumed triplet origin is consistent with theoretical predictions, and observed several previously unreported triplet levels for CHCl and CDCl. We report in this work the first high resolution spectra of singlet-triplet transitions in CH³⁵Cl, obtained using stimulated emission pumping (SEP) spectroscopy from selected rovibrational levels in the A¹A'' state. Our spectra reveal detailed information on the rovibrational structure of the triplet state levels, and a pronounced vibrational state dependence of the spin-spin splitting, which is a sensitive probe of spin-orbit coupling with nearby singlet levels. The derived singlet-triplet gap and triplet rovibronic and spin parameters are compared with the results of recent high level ab~initio calculations.