The first set of theoretical rotational cross sections for propylene oxide (CH3CHCH2O) colliding with cold He atoms has been obtained at the full quantum level using a high-accuracy potential energy surface. By scaling the collision reduced mass, rotational rate coefficients for collisions with para-H2 are deduced in the temperature range 5-30 K. These collisional coefficients are combined with radiative data in a non-LTE radiative transfer model in order to reproduce observations of propylene oxide made toward the Sagittarius B2(N) molecular cloud with the Green Bank and Parkes radio telescopes. The three detected absorption lines are found to probe the cold (∼10 K) and translucent (nH ∼2000 cm-3) gas in the outer edges of the extended Sgr B2(N) envelope. The derived column density for propylene oxide is Ntot ∼3 x 1012 cm-2, corresponding to a fractional abundance relative to total hydrogen of ∼2.5 x 10-11. The present results are expected to help our understanding of the chemistry of propylene oxide, including a potential enantiomeric excess, in the cold interstellar medium.
K. Dzenis and A. Faure and B. A. McGuire and A. J. Remijan and P. J. Dagdigian and C. Rist and R. Dawes and E. Quintas-Sánchez and F. Lique and M. Hochlaf, "Collisional Excitation and Non-LTE Modeling of Interstellar Chiral Propylene Oxide," Astrophysical Journal, vol. 926, no. 1, article no. 3, Institute of Physics - IOP Publishing, Feb 2022.
The definitive version is available at https://doi.org/10.3847/1538-4357/ac43b5
International Standard Serial Number (ISSN)
Article - Journal
© 2022 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
01 Feb 2022