Radiative charge transfer in collisions of C with He+

TL;DR

This paper presents a theoretical study of radiative charge transfer between carbon atoms and helium ions, providing detailed quantum calculations and results relevant for astrophysical environments like PDRs and XDRs.

Contribution

It offers new quantum chemistry calculations of potential energy curves and transition dipole moments for HeC+ states, and computes charge transfer cross sections and rate coefficients.

Findings

Large radiative charge transfer cross sections at low energies

Results applicable to modeling interstellar PDRs and XDRs

Potential impact on understanding CO and C+ abundances

Abstract

Radiative charge exchange collisions between a carbon atom C(${}^3$P) and a helium ion He+, both in their ground state, are investigated theoretically. Detailed quantum chemistry calculations are carried out to obtain potential energy curves and transition dipole matrix elements for doublet and quartet molecular states of the HeC+ cation. Radiative charge transfer cross sections and rate coefficients are calculated and are found at thermal and lower energies to be large compared to those for direct charge transfer. The present results might be applicable to modelling the complex interplay of [C II] (or C+), C, and CO at the boundaries of interstellar photon dominated regions (PDRs) and in xray dominated regions (XDRs), where the abundance of He+ affects the abundance of CO.