Theoretical Treatment of Penning Ionization—He(1s2s 1S, 3S) + H(1s 2S)

The potential curves involved in the Penning ionization of the hydrogen atom by helium metastables have been computed by a large-scale configuration interaction. These are the potentials of the He–H system which dissociate to a ground-state H atom and He atom in the four states 1s2s1S,3S,1s2p1p,3p; the ground-state He–H+ potential curve is also required. A simplified description of the ionizing collision is introduced which permits the determination of approximate cross sections (total ionization cross sections, associative ionization cross sections, the energy distribution of the ionized electron, etc.) without knowledge of the autoionization rate; numerical applications to the He* + H system are presented.