Electron capture by state-selected O2+ ions from atomic hydrogen

Abstract

Ab initio methods are used to obtain the adiabatic potential energies and the corresponding non-adiabatic radial and rotational coupling matrix elements for all of the doublet and quartet Sigma , Pi and A states of OH2+ which contribute to electron capture by state-selected O2+ from atomic H. Semiclassical methods are used to treat the collision dynamics. Results are presented both for ground (3P) and metastable (1D,1S) state ions in the range of collision energies from 20 eV to 30 keV. The cross sections for electron capture by ground state ions are about a factor of three larger than for metastable ions over a very wide energy range. The effect of rotational mixing of the 4 Sigma - and 4 Pi states in the entry channel for ground state ions is found to be large at energies in excess of a few 100 eV. The results are in excellent agreement with the experimental energy gain spectra.