Associative Ionization in Slow Collisions between Atoms. I

Abstract

Associative ionization through slow collisions of an atom with a metastable atom is investigated theoretically, in which the excitation energy of an excited atom is larger than the ionization potential of the other atom. The process is dealt with by the local complex potential method, since in this case the initial discrete electronic state is a resonance state because of the coupling with a degenerate continuum. Cross section formulas are obtained for a molecular ion formation with specified rotational and vibrational quantum numbers (j, v) and a total associative ionization. As a demonstration the method is applied to the system He^*(2³S, 2¹S)+H. Population inversion with respect to vibrational levels is expected to occur fairly effectively in these processes.