ROTATIONAL FINE STRUCTURE IN THE FLUORESCENCE EXCITATION SPECTRUM OF TOLUENE

Abstract

Experimental measurements have been reported the $S_{1} - S_{0}$ fluorescence excitation spectrum of $toluene^{1}$ which reveal forbidden bands corresponding to excited levels of the methyl internal rotation mode. We present theoretical predictions of the rotational fine structure of these bands, incorporating ab initio and least-squares-fitted geometrical structures for the $S_{0}$ and $S_{1}$ states. We particularly consider the coupling of overall and internal rotation, and the direct calculation of individual rovibronic line intensities.