Correlation in double electron capture in collisions of fully stripped ions on He andH2

Abstract

Energy spectra of electrons resulting from collisions of bare ions ${\mathrm{C}}^{6+}$+${\mathrm{H}}_2$ and ${\mathrm{O}}^{8+}$+He are presented. A detailed analysis is given for those parts of the spectra that are due to two-electron capture into (3l,3l’) configurations of the He-like projectile ions and subsequent autoionization. Measured peaks are uniquely identified by comparison with existing theoretical calculations. Based on a detailed investigation, it is concluded that an influence of interference effects on the spectra cannot be identified. A quantitative fit of the spectra allows us to determine the population probabilities of the various states with (3l,3l’) configuration. We find a preferential population of states that can be characterized by a correlated electronic motion with the two electrons on opposite sides of the capturing ion and rotating in the same sense. This result is discussed in terms of a classical picture for the capturing process.