Quantum theory of vector correlations in vibrationally mediated photodissociation

Abstract

The quantum treatment of the photodissociation of aligned, vibrationally excited molecules prepared by polarized laser excitation is presented. A formal expression for the angle-dependent multipole moments of a photofragment is derived. As a specific example, the projection of the laboratory angular distribution (zero-order moment) along a probe direction is considered, and Doppler-shift-dependent fluxes for various arrangements of the polarization directions of the vibrational excitation and photolysis lasers are computed. The profiles depend upon the photodissociation dynamics only through the conventional recoil anisotropy parameter β, as in one-photon dissociation. More generally, the dynamical information obtainable from measurement of vector correlations in VMP is the same as that which can be extracted in a one-photon dissociation experiment. Nevertheless, measurement of vector correlations for vibrationally mediated photodissociation can provide new information on the dissociation dynamics since different regions of the excited potential energy surface(s) are accessed from those accessed in one-photon dissociation.