Charge-exchange processes in collisions of ${\mathrm{H}}^{+},\phantom{\rule{4pt}{0ex}}{\mathrm{H}}_{2}^{+},\phantom{\rule{4pt}{0ex}}{\mathrm{H}}_{3}^{+},\phantom{\rule{4pt}{0ex}}{\mathrm{He}}^{+}$, and ${\mathrm{He}}_{2}^{+}$ ions with CO and ${\mathrm{CO}}_{2}$ molecules at energies below 1000 eV

Charge-exchange processes in collisions of $H^{+}, H_{2}^{+}, H_{3}^{+}, {He}^{+}$ , and ${He}_{2}^{+}$ ions with CO and ${CO}_{2}$ molecules at energies below 1000 eV

S. Werbowy and B. Pranszke

Phys. Rev. A 93, 022713 – Published 26 February 2016

Abstract

Absolute measurements of charge-exchange cross sections of $H^{+}, H_{2}^{+}, H_{3}^{+}, {He}^{+}$ , and ${He}_{2}^{+}$ ions in CO and ${CO}_{2}$ have been made for energies below 1000 eV, an equivalent of the energy of ionized particles at typical solar-wind conditions. An attenuation method for the case of complex ions of a molecule, taking into account the influence on the ion beam composition of the processes of disintegration of the primary ions into secondary ones with different charge-exchange cross sections, is described. Also the secondary effects, like three-body collisions and re-ionization processes that could emerge at higher pressures of the gas layer, are discussed. Dependence of the cross sections on the number of atomic centers in the projectile have been explained on the basis of the energy defect of the reactions and asymmetric near-resonant charge-exchange process between the ion and target molecule including the Doppler broadening in the interaction of the monoenergetic ion beam and target molecules having an isotropic Maxwellian velocity distribution corresponding to room temperature. Using the semiempirical approach based on the parametrized numerical coupled-channel two-state calculations, we have extrapolated the cross sections to a broader range of velocities.