State-selective electron capture by slow C³⁺and N³⁺ions in H and H₂

Translational energy spectroscopy (TES) in a furnace target arrangement (previously developed in this laboratory) has been used to identify the main collision channels in the process of one-electron capture by C 3+ and N 3+ ions in H and H 2 within the energy range 1.5-18 keV. A higher energy resolution than in previous measurements and a greatly increased product-ion detection efficiency has been achieved by the use of a position-sensitive detector. Additional features are observed in the energy-change spectra for C 3+ in H and the results allow a more detailed comparison with the theoretical predictions of Bienstock et al. (1982-4) and recent experimental measurements of Ciric et al. (1985) based on the complementary technique of photon emission spectroscopy (PES). A detailed analysis of the results for N 3+ impact is complicated by the presence of collision channels involving both ground-state and metastable primary ions. Nevertheless, important collision channels not predicted by theory are observed in both H and H 2 .