Angular distributions from photodissociations. V. The bent triatomic molecule

Abstract

The generalized Franck–Condon theory of bent triatomic molecule dissociations is extended to permit the calculation of state‐to‐state photofragment angular distributions. The axial recoil limiting forms of Zare and Bersohn are obtained for the state‐averaged angular anisotropies β̄ with corrections for the effects of bending vibrations. For certain orientations of the transition dipole within the molecule, β f i is found to be nearly independent of fragment rotational angular momentumj, while for other orientations, it is found to be a strongly oscillatory function of j. In some cases, calculated photofragment rotational distributions at fixed detection angles are strong functions of the detection angle, suggesting the possibility of partial state selection by spatial resolution. Approximate analytical expressions for β f i are presented for initially bound molecular states that are either nonrotating or are well described by a prolate symmetric top wave function with k=0. The distributions are linear combinations of parallel and perpendicular‐type distributions. Numerical applications are provided for direct photodissociations from the bent X̃ HOC1 and C̃ HCN states.