PROBING THE DYNAMICS IN THE FRANCK-CONDON REGION AND EXIT CHANNEL REGIONS OF DISSOCIATING $H_{2}S$: RESONANCE RAMAN SPECTRA AT EXCITATION WAVELENGTHS FROM 199-203 NM

Abstract

Resonance Raman spectra of $H_{2}S$ at excitation energies near 200 nm probe the dissociation dynamics from a conical intersection in the Franck-Condon region to the H + SH product exit $channel^{1}$. The dramatic change in the observed spectra as one tunes through this small region of the broad absorption band reflects the rapid change in electronic character of the excited state region accessed at these energies. It is in this region that the bright, bound state initially accessed crosses and couples to a dark, dissociative state. An analysis of these spectra in conjunction with recent scattering calculations by $Heumann and Schinke^{2)$ allows us to pinpoint the energetic region of the conical intersection of these two surfaces and to understand the evolution of the photodissociation dynamics from the initial bound state to the exit channel leading to dissociation.