Vibrational assignments for indole with the aid of ultrasharp phosphorescence spectra

A site-selective study of the L-3(a) phosphorescence from indole in solid a rgon at 20 K has revealed a special site from which the emission is excepti onally sharp (5 cm(-1) fwhm). These spectra are compared with well-resolved (5 cm(-1) fwhm) fluorescence from the L-1(b) origin of indole under cold j et conditions. The results are compared with frequencies and Franck-Condon factors generated from ab initio electronic structure calculations on the g round and excited states. On the basis of the data and calculations, new as signments are made. (C) 1999 John Wiley & Sons, Inc.