Semiclassical calculation for collision induced dissociation

Abstract

The classical S‐matrix theory of Miller and Marcus has been used to compute collision induced dissociation probabilities (P^diss) for particle–oscillator one dimensional collisions. The continuum of dissociation states was discretized in a straightforward way by confining the oscillator to a suitably large box. From this simple discretization an expression for P^diss in the limit of an infinite box is derived. Numerical results for a truncated harmonic oscillator with an exponential repulsive interaction with the colliding particle are presented for several masses and potential parameters. The behavior of P^diss as a function of collision energy, well depth and initial vibrational excitation is studied. The energy profile of P^diss shows a prominent structure which is directly related to the initial vibrational state of the oscillator. The relative dissociation ’’efficiencies’’ of the different vibrational levels of the oscillator depend drastically on the collision energy, with highly excited vibrational states being more ’’efficient’’ dissociation candidates at low (near threshold) energies but with the opposite behavior at higher kinetic energies. The dependence of the dissociation probability on potential parameters and masses is analogous to the trends for a comparable energy transfer process.