VIBRATIONAL PROPENSITY IN THE PREDISSOCIATION RATE OF SO2((C)OVER-TILDE(1)B(2)) BY 2 TYPES OF NODAL PATTERNS IN VIBRATIONAL WAVE-FUNCTIONS

The absorption and laser-induced fluorescence spectra of the (C)over-t ilde(1)B(2)-(X)over-tilde(1)A(1), band of SO2 were simultaneously meas ured between 221.5 and 208 nm under jet-cooled conditions. The fluores cence quantum yields above the dissociation threshold showed irregular ity, reflecting a level specificity in the predissociation rate. The v ibronic-level dependence in the predissociation rate was interpreted i n terms of the nodal structure of the vibrational wavefunctions, const ructed from a least-squares analysis of the observed vibrational energ ies in the C state. The vibrational wavefunctions can be categorized i nto two types of localized wavefunctions: one stretching along the dis sociation coordinate which tends to afford a much faster dissociation rate than the other which folds perpendicularly to the dissociation co ordinate. (C) 1998 Elsevier Science B.V. All rights reserved.