Ionisation processes in collisions of open shell atoms. II. Oxygen and sulphur atom collisions with inert gases

Abstract

For pt.I see ibid., vol.23, p.279 (1990). Results of an electron spectroscopy study of ionisation processes, in low keV collisions of oxygen and sulphur atoms with inert gases are presented. It is shown that ionisation close to threshold is dominantly due to population of singly excited autoionising states of the 2D(2P)nl series. At energies that are significantly above the threshold for excitation processes an additional ionisation channel which leads to a continuous electron energy distribution becomes important. A discussion in terms of the molecular orbital model is presented and indicates that quasimolecular Auger ionisation could be an efficient positive-ion production mechanism at high energies. A comparison with O- and S- collisions is conducted.