The ground state vibrational structure of SCCl2:: observation of backbone IVR

Vibrationally excited SCCl2 is a model system for energy redistribution among backbone vibrational modes. Over 200 transitions in the X̃←B̃ dispersed fluorescence spectrum of thiophosgene have been observed to map the ground electronic surface up to 15000 cm−1. An analytical six-dimensional potential surface derived from ab initio calculations has been fitted directly to about 100 of the transitions to provide an experimentally derived surface for intramolecular vibrational energy redistribution (IVR) quantum dynamics calculations. Higher resolution stimulated emission pumping spectra from different vibrational levels in the B̃ state reveal a complex progression from unfragmented/slightly Fermi-resonant states, to highly fragmented states above v1=8.