Knowledge Bank

The $S0-T1$ electronic transition in $CH3CHS,CD3CHS,CH3CDS,CD3CDS$ has been observed in a continuous supersonic pyrolysis jet as a laser phosphorescence excitation spectrum. The potential surface for the torsional - wagging internal coordinates were mapped out with ab initio molecular orbital calculations with a $6-31G\ast$ basis in which the structural parameters were fully relaxed. The kinetic and potential energy data points were fitted to analytical double fourier expansions. These were incorporated into a two - dimensional Hamiltonian matrix in the torsion and wagging coordinates and symmetrized by the $G6$ point group and solved for the energies and wavefunctions. The spectrum calculated from the the frequencies and Franck - Condon factors was fitted to the observed ``hot” and cold band spectra and refinements were made to the potential surface.""