Quantum Calculation of Inelastic CO Collisions with H. II. Pure Rotational Quenching of High Rotational Levels

TL;DR

This paper presents new quantum scattering calculations for CO rotational deexcitation by H, providing comprehensive rate coefficients across a wide temperature range, crucial for astrophysical spectral analysis.

Contribution

It introduces updated, detailed quantum scattering data for CO-H collisions using a high-quality potential energy surface, covering high rotational levels and broad temperature ranges.

Findings

New rate coefficients for CO rotational deexcitation from j=1 to 45.

Comparison showing improvements over previous PES-based results.

Data applicable for astrophysical spectral modeling.

Abstract

Carbon monoxide is a simple molecule present in many astrophysical environments, and collisional excitation rate coefficients due to the dominant collision partners are necessary to accurately predict spectral line intensities and extract astrophysical parameters. We report new quantum scattering calculations for rotational deexcitation transitions of CO induced by H using the three-dimensional potential energy surface~(PES) of Song et al. (2015). State-to-state cross sections for collision energies from 10$^{-5}$ to 15,000~cm$^{-1}$ and rate coefficients for temperatures ranging from 1 to 3000~K are obtained for CO($v=0$, $j$) deexcitation from $j=1-45$ to all lower $j'$ levels, where $j$ is the rotational quantum number. Close-coupling and coupled-states calculations were performed in full-dimension for $j$=1-5, 10, 15, 20, 25, 30, 35, 40, and 45 while scaling approaches were used to estimate rate coefficients for all other intermediate rotational states. The current rate coefficients are compared with previous scattering results using earlier PESs. Astrophysical applications of the current results are briefly discussed.