Quantum-mechanical study of rotational and vibrational transitions in CO induced by H atoms

We report rate coefficients for rotational and vibrational transitions in CO induced by H atoms using quantum-mechanical scattering calculations and the H-CO interaction potential of Keller et al. We use the infinite-order sudden approximation for vibrational transitions and the close-coupling method for rotational transitions. Rate coefficients are presented for temperatures 5 K < T < 3000 K. Differences of a factor of 30 are found for rate coefficients for low temperatures below 100 K compared to earlier results of Green and Thaddeus. The discrepancies are attributed to the differences in the details of the interaction potentials, especially the long-range part to which the low-temperature rate coefficients are most sensitive. There is good spectroscopic evidence that the potential-energy surface employed here reproduces the resonance energies and widths of the HCO system better than any previously available HCO interaction potentials.