Photofragmentation of linear triatomics

Abstract

This paper is concerned with a complete quantum mechanical treatment for the photofragmentation of linear triatomic molecules, going beyond the Golden rule calculation and quasidiatomic approximation. Harmonic valence type potentials are assumed for the bound motions, while an exponential potential describes the unbound motion. An analytical expression for the final vibrational distribution is obtained. This explicitly incorporates the final states interactions which are responsible for the V–T energy transfer during the half‐collision following the bond breaking. The two‐dimensional Franck–Condon factors are evaluated using the Airy approximation, and a simplified statistical procedure to incorporate rotational distributions is presented. This treatment is applied to the photodissociation of ICN and HCN, and the effects of deuteration on linewidths are analyzed. A fit to the available experimental probability distribution leads to physically acceptable parameters for the repulsive potential.