Abstract

The close-coupled theory of scattering in a radiation field can be successfully used to predict excited atomic alignment (orientation) and fine structure branching when linearly (circularly) polarized laser light is absorbed by the transient quasi-molecule formed during a strong atomic collision. Specific calculations based on ab initio molecular potentials have been carried out for Sr + Ar and Na + He and Ar. Generally good agreement is found between calculated and measured branching fractions as a function of detuning up to several hundred cm^-1 from the atomic resonant transition frequency. An analysis of the scattering wave function shows how the transition amplitudes can be factored into separate parts representing Franck-Condon excitation and half-collision dynamics, as for photodissociation phenomena. A simple recoil limit applies when the atoms separate in a time short compared to the time scale of angular momentum recoupling. Departures from the recoil limit can be explained in terms of axis rotation dynamics and the crossing of molecular Born-Oppenheimer potential curves.

© 1986 Optical Society of America