Direct and charge exchange inelastic processes in ion-atom collisions. II. He+-Ne

For pt.II see ibid., vol.9, p.269 (1976). The He+-Ar collision is studied experimentally in the 100-2000 eV laboratory energy range. Differential cross sections sigma ( theta ) are determined for the main inelastic processes. Direct excitations of Ar are identified by the electrostatic energy analysis of the scattered ions and charge-exchange processes are investigated by a time-of-flight technique. The He+-Ar system differs markedly from the He+-He and He+-Ne collisions previously studied by the importance of the charge-exchange processes into excited states of Ar+ and by the weakness of the charge exchange in the ground state. Ab initio potential energy curves and differential cross section calculations confirm the proposed excitation mechanism, at least for moderate-energy collisions.