Theory of coherences produced by radiatively assisted inelastic collisions: Weak-field impact-core limit

A theoretical calculation of the final-state coherences produced by a radiatively assisted inelastic collision (RAIC) is presented. Two atoms, A and A', collide in the presence of an external radiation field to produce the RAIC reaction A/sub i/+A/sup prime//sub i/'+hΩ→A/sub f/+A/sup prime//sub f/', where in equilibriumi'> is the initial state, ff'> is the final state, and Ω is the frequency of the external field. It is assumed that the final states consist of a number of nearly degenerate levels and the coherences produced in these levels by the RAIC reaction is calculated. These final-state coherences can be monitored by standard techniques (polarization of fluorescence, quantum beats) enabling one to use the final-state coherences as a probe of the RAIC reaction. The calculation is limited to the weak-field (perturbation-theory) limit and is valid only in the impact core of the RAIC profile