Theory of Atomic Collisions with Negative Ions: Associative Detachment

In this paper we consider the problem of atomic collisions with negative ions and give special attention to the rearrangement process of associative electron detachment. After the various possible processes, the interaction potentials, and the related problems of potential curves are described physically, a theoretical formulation of the problem is presented, ranging from general formalism to explicit formulas for the reaction cross section and the rate coefficient. In the general formalism, transition matrices are derived for direct and resonance reactions as well as for potential and resonance scatterings. The process of associative detachment is then treated explicitly, using these derived expressions. It is shown that because of the configuration interaction of the electronic motion with continua, the nuclear motion is taking place in a complex potential. The propagation of a nuclear state in such a complex potential is treated in some detail. Various implications of the derived theoretical results are discussed in connection with experimental observations.