Nonadiabatic Electronic Interactions In The Ion-Pair States Of NelCl

Abstract

Nonadiabatic interactions in the NeIC1 van der Waals complex have been explored in the lowest energy triad of IC1 ion-pair states (approximately 39 000 cm-1). Dispersed fluorescence measurements reveal emission characteristic of multiple ion-pair electronic states, with the relative contributions from the E(O+ ), beta(1), and D\u27(2) states changing with the initial IC1 vibrational excitation (v(IC1)). Emission directly from NeIC1 (v(IC1) = O) complexes indicates that the initially prepared NeIC1 levels have mixed electronic character and that the IC1 electronic parentage changes with the initial van der Waals vibrational level selected. NeIC1 complexes prepared with 1-4 quanta of IC1 stretch undergo rapid vibrational predissociation with a strong propensity for DELTA-V(IC1) = - 1 relaxation. The electronic state(s) populated in the IC1 fragments differ from the mixed electronic character of the initially prepared level, demonstrating that vibrational predissociation is accompanied by nonadiabatic electronic state changing processes. The observed final state selectivity may be attributed to the relative strength of the nonadiabatic couplings between the initial NeIC1 bound state and the final IC1 states or a momentum gap rationale based on the overlap between the NeIC1 bound state wave function and the highly oscillatory continuum wave function of the separating fragments