State-selective capture by slow Ar4+, Ar5+ and Ar6+ recoil ions in H, H2 and He

Translational energy spectroscopy has been used to study the distribution of excited product ion channels in one-electron capture by Ar4+, Ar5+ and Ar6+ in H, H2 and He at qx1 keV. Primary ions with the required small energy spread have been obtained from a recoil ion source. The authors have calculated 'reaction windows' based on the dependence of the single-crossing Landau-Zener cross section on the crossing distance. Multichannel Landau-Zener calculations have also been carried out to obtain cross sections for capture into specific states. The calculations are shown to be in reasonable accord with the present observed energy change spectra. (author)