Role of cascade and Auger effects in the enhanced population of theC3+(1s2s2p4P)states following single-electron capture inC4+(1s2s3S)-He collisions

Abstract

The population of excited three-electron states in carbon ions after single-electron capture in $0.5\ensuremath{-}1.1$ MeV/amu ${\mathrm{C}}^{4+}(1s2s {}^{3}S)$-He collisions is analyzed theoretically by combining different methods. While the two-center basis generator method is used to calculate capture amplitudes on the single-particle level, all-electron structure calculations for the relevant ${\mathrm{C}}^{3+}$ states and their radiative and Auger transition rates are performed on the multiconfiguration Dirac-Fock level. These data are then combined and fed into a set of classical rate equations for the decay dynamics. Total cross sections for the production of the $1s2s2p {}^{4}P$, $1s2s2p {}^{2}{P}_{\ensuremath{-}}$, and $1s2s2p {}^{2}{P}_{+}$ states are calculated and their ratios compared with recent experimental data and previous calculations [D. Strohschein et al., Phys. Rev. A 77, 022706 (2008)]. It is found that the relative intensities of the $1s2s2p {}^{4}P$ states are considerably larger than expected on the basis of pure spin statistics. The Auger transitions, which were not included in the previous calculations, have a significant effect on the final results in that they reduce the $1s2s2p {}^{2}P$ intensities. Although our extended computations explain a significant part of the production of the $1s2s2p {}^{4}P$ states, the experimentally observed enhancement of these states is still considerably larger than the theoretical one.