Radiative association of C(3P) and H+: triplet states

The radiative association of C(³P) and H⁺ is investigated by calculating cross-sections for photon emission into bound ro-vibrational states of CH⁺ from the vibrational continua of initial triplet d ³Π or b ³Σ^- states. Potential energy curves and transition dipole moments are calculated using multireference configuration interaction (MRCI) methods with AV6Z basis sets. The cross-sections are evaluated using quantum-mechanical methods and rate coefficients are calculated. The rate coefficients are about 100 times larger than those for radiative association of C⁺(²P^o) and H from the A ¹Π state. We also confirm that the formation of CH⁺ by radiative association of C⁺(²P^o) and H via the triplet c ³Σ⁺ state is a minor process.