Fine-structure-resolved Rovibrational Excitation of OH due to Collisions with H₂ and He

In this work, we present preliminary scattering calculations of OH with H₂ using a new full-dimensional potential energy surface. State-to-state rate coefficients for rovibrational transitions computed within a 5D coupled-states approximation are benchmarked against those obtained by using a quantum close-coupling method. Fine-structure and lambda-doubling are incorporated dynamically in the calculations.

We also present rate coefficients for vibrational transitions of OH due to He. Quasiresonant vibration-rotation transitions for relatively large rotational states near j=35.5 are discussed. In some cases, vibrationally inelastic cross-sections dominate over pure rotational transitions.

The calculations presented here are motivated by recent observations from the James Webb Space Telescope, which include spectra corresponding to the fundamental OH rovibrational band. State-to-state collisional rate coefficients with abundant perturbers are needed to interpret spectra taken from non-local thermodynamic equilibrium environments.