An experimental study of exited state formation in collisions between low energy (<25 keV amu-1) state-prepared multiply charged ions and simple atomic and molecular targets

The technique of Double Translational Energy Spectroscopy has been used to study state selective one-electron capture by multiply charged ions, C2+ , N2+ and O2+, from simple atomic and molecular targets using state-prepared ion beams at various energies between 1.75 keV and 8 keV. In each case the main collision channels have been identified and their relative importance has been assessed quantitatively. The results have been compared with other experimental data where available. The use of pure beams of ground state ions or pure beams of metastable species avoids the ambiguities inherent in the interpretation of previous Translational Energy Spectroscopy that have been carried out using primary ion beams containing a mixture of ground and metastable species. Theoretical Landau-Zener reaction windows have been calculated for the processes studied. It was seen that the reaction windows accommodate the observed collision channels with limited success. A simple beam attenuation technique has also been used in conjunction with the state-prepared beams of C2+ to provide estimates of the ratio of the total one-electron capture cross-sections σ (3P)/σ (1S) in collisions with He, Ne and Ar. In each case it has been shown that σ (3P) is considerably larger than σ (1S). These ratios have in turn been used to show that the content of metastable ions from the ECR ion source used in the course of these studies can be substantial. (author)