State-selective Charge Transfer Studies Relevant to Solar Wind–Comet Interactions

Abstract

We report relative experimental and absolute theoretical n-state-selective, nondissociative, single-electron capture cross sections for a number of collision systems typical of the solar wind-comet interactions. The experimental 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 the He atomic target. The theoretical calculations were performed using the classical trajectory Monte Carlo (CTMC), the Landau-Zener (LZ), and the classical over-the-barrier (COB) models. The models, with CTMC favored, agree reasonably well with the measurements and can be used in the near term to aid in the modeling of cometary X-ray and EUV emission. The pathways through which multiple-electron capture processes contribute to the cometary X-ray and EUV emission are also discussed.