Electron transfer reactions in collisions of low energy Neq+ (q=3-5) ions with CO2 and H2O molecules

Collision spectroscopy has been used to measure energy spectra and absolute total cross sections for single- and double-electron transfer reactions in low-energy collisions of Neq+ (q =3-5) ions with CO2 and H2O at impact energies between 15 and 500q eV, where q is the projectile charge state. The energy spectra show that only a few final states were selectively populated depending on the charge state of the projectile. In all collision systems studied here, the dominant reaction channels are due to nondissociative single-electron transfer into excited states of the projectile product. For collisions of Ne3+ and Ne4+ ions with CO2 and H2O reaction channels correlated with transfer excitation were also observed. The energy dependence of cross sections for single- and double-electron transfer are also measured and found to slowly increase with increasing impact energies:The measured cross sections for single-electron transfer are also compared with theoretical calculations of the Multichannel Landau-Zener (MCLZ) model and the classical over the barrier (COB) model. The projectile charge state dependence of the cross section ratio of double to single-electron transfer increases with increasing the charge state in disagreement with the calculations based on an extension of the classical over-the-barrier model to multi-electron transfer, which predicts that the-ratio is independent of the charge state. (C) 2015 Elsevier B.V. All rights reserved.