Theory of associative ionization

Abstract

The theory of atomic associative ionization (AI) presented here is a many-channel treatment incorporating radial Born-Oppenheimer and Coriolis couplings among the reactant channels as well as analogous couplings among the ionized, final states. Careful attention is paid to characterizing the basis sets used to represent the pre- and post-collisional states, especially with regard to the internal and relative angular momenta of the fragments. Particularly noteworthy in this context is our use of a total angular momentum representation. This representation is excellently adapted to the derivation of selection rules needed in the analysis of AI experiments involving atoms excited into oriented hyperfine states by means of polarized lasers. Selection rules previously obtained by heuristic means are derived more rigorously here. Finally, explicit and compact formulas are constructed for the lowest-order (two-state) approximation to the AI scattering amplitude and for the first-order Born-Oppenheimer corrections as well.