State-selective electron capture by slow C4+ ions in collisions with H2 and O2

Abstract

Translational energy spectroscopy has been used to study state-selective one-electron capture by C4+ ions in collisions with H2 and O2 at impact energies of 4, 8 and 16 keV. The main excited product channels have been identified and their relative importance assessed. In the case of H2, capture into the n=3 states of C3+ is predominant and separate cross sections for capture into the C3+(1s2)3s, 3p and 3d states have been determined by reference to previously measured total cross sections. The authors' measured cross sections are in good agreement with previous measurements based on photon emission spectroscopy and with the predictions of quantal calculations. In the case of O2, where no previous measurements exist, capture into the n=3 states of C3+ is again predominant with a small n=4 contribution at 4 and 8 keV. The authors' measurements in both H2 and O2 show H+2 and O+2 product ion formation via Franck-Condon transitions.