A full-dimensional quantum dynamical approach to the vibrational predissociation of Cl2–He2

Abstract

A full-dimensional, fully coupled wave packet method is proposed and applied to investigate the vibrational predissociation dynamics of the Cl2(B,v')-He2 complex. Simulations are carried out for the resonance states associated with the v'=10-13 initial vibrational excitations of Cl2, and the results are compared with the available experimental data. A good agreement with experiment is achieved for the resonance lifetimes (typically within experimental error) and the Cl(2) fragment rotational distributions. The mechanism of dissociation of the two He atoms is found to be dominantly sequential, through the Deltav'= -2 channel. The probabilities obtained for the Deltav'= -1 dissociation channel are, however, overestimated due to the use of absorbing boundary conditions combined with finite grid effects. It is suggested that a mechanism of energy redistribution through the couplings between the van der Waals modes of the two weak bonds takes place in the Deltav'= -1 dissociation. This mechanism is consistent with the resonance lifetimes and Cl2 rotational distributions predicted. The favorable comparison with most of the experimental data supports the reliability of the potential used to model Cl2(B,v')-He2, at least in the present range of v' levels.