Calculation of Collisional Dissociation of Alkali Halide Molecules by Classical One-Dimensional Models

Abstract

Classical one‐dimensional calculations have been carried out to estimate the rate of dissociation of CsBr by collisions with Xe, as a function of collision energy and vibrational energy. Three models have been used: a truncated harmonic oscillator for CsBr with impulsive collisions with Xe, a Rittner‐type ionic potential for CsBr with impulsive collisions with Xe, and a Rittner‐type potential for CsBr with a soft (12–4–6) potential representing collisions with Xe. Results are in qualitative agreement with the experimental findings of Tully et al., but poor quantitative agreement implies that the problem requires a three‐dimensional treatment for proper description, and, near threshold, probably inclusion of charge exchange in the potential. The calculations show very clearly how kinematic constraints prevent collisions near threshold energy from dissociating molecules which have little or no vibrational energy. The dependence of the dissociation probability on the vibrational temperature is also discussed. It is shown that, in some cases, a negative temperature dependence may arise.