Fundamental processes in collisions of O-with atoms and molecules; mechanisms of one- and two-electron loss

The authors present results of a study of O + and O production in low-energy (10-5000 eV) collisions of O - with He, Ne, Ar, Kr, Xe, N 2 and H 2 . An electron spectroscopy study reveals excitation of a series of singly excited autoionising states of the oxygen atom whose decay leads to O + production. The electron spectra show that the cross section for O + production in some cases can be appreciable even at collision energies as low as 100 eV. This is confirmed by measurements of total cross sections for one- and two-electron loss. For the N 2 target, charge exchange to the N 2 shape resonance is also observed.