State-selective charge transfer studies relevant to solar wind-comet interactions

We report relative experimental and absolute theoretical n-state-selective, nondissociative, single-electron capture cross sections for a number of co llision systems typical of the solar wind-comet interactions. The experimen tal measurements were carried out using the technique of cold-target recoil -ion momentum spectroscopy and involved the N7+ and O7+ projectile ions and , for the first time, the H2O, CO2, and CO molecular targets, as well as th e He atomic target. The theoretical calculations were performed using the c lassical trajectory Monte Carlo (CTMC), the Landau-Zener (LZ), and the clas sical over-the-barrier (COB) models. The models, with CTMC favored, agree r easonably well with the measurements and can be used in the near term to ai d in the modeling of cometary Xray and EUV emission. The pathways through w hich multiple-electron capture processes contribute to the cometary X-ray a nd EUV emission are also discussed.