Hyperfine excitation of CH and OH radicals by He

Article


Marinakis, S., Kalugina, Y., Klos, J. and Lique, F. 2019. Hyperfine excitation of CH and OH radicals by He. Astronomy and Astrophysics. 629 (Art. 130).
AuthorsMarinakis, S., Kalugina, Y., Klos, J. and Lique, F.
Abstract

Context. Because of their high reactivity, the CH and OH radicals are of particular interest in astrochemistry. Modelling of CH and OH requires the calculation of accurate radiative and collisional rate coefficients for (de)excitation by collisions with the most abundant species such as H₂ and He.
Aims. The present paper focuses on the calculation of inelastic rate coefficients among the lowest OH/CH hyperfine levels in their ground vibrational state in collisions with He atoms.
Methods. Calculations of hyperfine (de)excitation of CH/OH by He were performed using the close-coupling and recoupling methods from the most recent ab initio potential energy surfaces.
Results. Cross sections for transitions among the 60 and 56 lowest hyperfine levels of CH and OH, respectively, were calculated for collision energies up to 2500 cm⁻¹. These cross sections were used to calculate the rate coefficients for temperatures between 10 and 300 K. A propensity rule for collisions with ∆F = ∆j was observed.
Conclusions. The new rate coefficients will help significantly in interpreting the CH/OH spectroscopic data observed with current and future telescopes, and help to describe accurately the OH masers and the hyperfine anomalies in CH emission spectra.

JournalAstronomy and Astrophysics
Journal citation629 (Art. 130)
ISSN0004-6361
Year2019
PublisherEPD Sciences for European Southern Observatory
Accepted author manuscript
License
File Access Level
Repository staff only
Publisher's version
License
File Access Level
Anyone
Digital Object Identifier (DOI)doi:10.1051/0004-6361/201936170
Web address (URL)https://doi.org/10.1051/0004-6361/201936170
Publication dates
Online16 Sep 2019
Publication process dates
Accepted25 Jul 2019
Deposited29 Jul 2019
FunderNational Science Foundation (NSF)
Agence Nationale de la Recherche
Russian Science Foundation
Programme National de Physique et Chimie du Milieu Interstellaire
Copyright holder© 2019 The European Southern Observatory
Copyright informationReproduced with permission from Astronomy & Astrophysics.
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