Electron capture in collisions of C⁺ with H and H⁺ with C

A comprehensive theoretical and experimental study of electron capture in collisions of C⁺ with H and H⁺ with C extending over the energy range 0.1 meV u^-1 to 1000 keV u^-1 is presented. A variety of theoretical approaches were used including those based on quantal molecular-orbital close-coupling (MOCC), multielectron hidden crossings (MEHC), quantal decay and classical trajectory Monte Carlo techniques. Radiative charge transfer cross sections were computed using the optical potential/distorted wave (OPDW) and fully quantal (FQ) approaches. The MOCC, OPDW and FQ calculations incorporated ab initio potentials, nonadiabatic coupling matrix elements and transition moments computed at the configuration-interaction level. Ab initio potential surfaces in the plane of complex internuclear distance were obtained for the MEHC calculations. Merged-beam measurements were performed between 75 eV u^-1 and 1.7 keV u^-1 for the C⁺/H(D) collision system. Diagnostics of the C⁺ beam with a crossed electron beam could find no presence of a C⁺ metastable component. The current results, in conjunction with previous measurements, are used to deduce a set of recommended cross sections.