Electron capture processes in slow collisions of Ne⁶⁺ ions with CO₂ and H₂O

Department of Physics, Western Michigan University - Kalamazoo, MI 49008-5252, USA

^a emanuel.kamber@wmich.edu

Received: 1 December 2010
Accepted: 3 January 2011

Abstract

Energy-gain spectra and absolute total cross-sections for single-, double-, and triple-electron capture processes in collisions of Ne⁶⁺ ions with CO₂ and H₂O at laboratory impact energies between 450 and 2400 eV, have been studied experimentally by means of a translational energy-gain spectroscopy technique. The energy-gain spectra for single-electron capture show that the dominant reaction channels are due to capture into the n = 4 state of Ne⁵⁺, in agreement with classical over-the-barrier model calculations. In both cases, contributions due to transfer excitation into the 2s2p (^1,3P) 3 l states are also detected. The energy-gain spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener (LZ) model and the extended version of the classical over-the-barrier (ECOB) model. The energy dependence of cross-sections for electron capture are also measured and found to be slowly increased with increasing collision energy. The data for single-electron capture are also compared with theoretical results based on the multi-channel Landau-Zener (MCLZ) model.