Formation of the CH/CD molecules through radiative association of C with H/D

Abstract

ABSTRACT Reaction rate constants have been calculated for the formation of CH and CD molecules through radiative association of C and H/D atoms in their ground states. Quantum mechanical and semiclassical/classical methods were used to obtain the reaction cross-sections. Shape resonances and inverse pre-dissociation are accounted for with Breit–Wigner theory. The potential, permanent/transition dipole moment curves and experimental pre-dissociation widths are taken from the literature. The resulting reaction rate constants were fitted to the Kooij formula for use in astrochemical modelling. Our rate constant is 3.5 × 10−17 cm3 s−1 at 100 K and it peaks at 20 K, where it is 8.0 × 10−17 cm3 s−1. These values are larger than what has been obtained in earlier studies but not large enough to account for the interstellar abundance of CH.