State-selective single-electron capture by Ar4+ and Ar5+ ions from N2, O2 and CF4 molecules

Single-electron capture processes in collisions of Arq+ ions with N2, O2 and CF4 have been studied experimentally at laboratory impact energies of 50 qeV (q = 4 and 5, where q is the projectile charge state) and scattering angles between 0° and 6° by means of a translational energy-gain spectroscopy technique. The translational energy-gain spectra show that the dominant reaction channels are due to non-dissociative single-electron capture into excited states of the projectile product Ar(q−1)+. However, at large scattering angles, other channels due to transfer excitation processes start to contribute significantly. The spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the Landau-Zener model and the extended version of the classical over-the-barrier model.