Quantum‐Mechanical Study of Rotational and Vibrational Transitions in CO Induced by H Atoms

N Balakrishnan,A Dalgarno,M Yan

doi:10.1086/321434

N Balakrishnan, A Dalgarno + Show 1 more

Open Access

https://doi.org/10.1086/321434

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Abstract

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.

Highlights

Excitation of rotational and vibrational levels of carbon monoxide occurs in a wide variety of astrophysical environments
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
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

Summary

Introduction

Excitation of rotational and vibrational levels of carbon monoxide occurs in a wide variety of astrophysical environments. 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.

Results

Conclusion