WEAK-INTERACTIONS AND PHOTOINITIATED UNIMOLECULAR DECOMPOSITION

Numerical studies have been carried out to examine the applicability o f the density of states measured just below dissociation threshold to transition state rate theory. The model system consists of two weakly interacting manifolds of levels, one of which is optically accessible. Both manifolds are coupled to dissociative continua. These studies de monstrate that immediately above reaction threshold, coupling to conti nua is relatively slow on the time scale of inter-manifold coupling, a nd it is the mixed manifolds which decay. At higher energies, coupling s to continua exceed inter-manifold couplings, and it is the photoexci ted bright states which undergo unimolecular decomposition. (C) 1998 E lsevier Science B.V. All rights reserved.