Hyperfine Excitation Of With P- Collisions

Tonolo, Francesca

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https://hdl.handle.net/2142/116541 Copy

Description

Title

Hyperfine Excitation Of With P- Collisions

Author(s)

Tonolo, Francesca

Contributor(s)

• Puzzarini, Cristina
• Barone, Vincenzo
• Melosso, Mattia
• Lique, François
• Bizzocchi, Luca

Issue Date

2022-06-23

Keyword(s)

Mini-symposium: Spectroscopy meets Chemical Dynamics

Abstract

The formyl ion (\ce{HCO+}) is one of the most abundant ions in molecular clouds and represents an excellent candidate to trace dense molecular gas through the evolutionary stages of the interstellar medium (ISM). For this reason, the accurate rotational rate coefficients of \ce{HCO+} and its isotopes with the most abundant perturbing species in the ISM are crucial in non-local thermal equilibrium (LTE) models and deserve special attention. To this end, many efforts have been made in order to retrieve accurate collisional parameters of \ce{HCO+} interacting with the \ce{He} and \ce{H2} colliders as well as for some of its isotopologues\footnote{Tonolo F., Bizzocchi L., Melosso M., Lique F., Dore L., Barone V., Puzzarini C., 2021, \emph{The Journal of Chemical Physics}, \textbf{155}, 234306.}$^,$\footnote{Denis-Alpizar O., Stoecklin T., Dutrey A., Guilloteau S., 2020, \emph{Monthly Notices of the Royal Astronomical Society}, \textbf{497}, 4276.}. However, in spite of laboratory and observational studies on \ce{HC^{17}O+}\footnote{Plummer G., Herbst E., De Lucia F., 1983, \emph{The Astrophysical Journal}, \textbf{270}, L99.}$^,$\footnote{Dore L., Cazzoli G., Caselli P., 2001, \emph{Astronomy \& Astrophysics}, \textbf{368}, 712.}, to the best of our knowledge, an accurate characterization of its collisional parameters has not been carried out yet. Although rarer, the \ce{HC^{17}O+} isotope assumes a prominent role to avoid problems due to the optical thickness of the parent species emissions. With the aim of filling this lack, this work reports the first calculations of hyperfine resolved rate coefficients for the excitation of \ce{HC^{17}O+} by $p$-\ce{H2} $(J=0)$.\\ We characterized the potential energy surface of the \ce{HCO+} and \ce{H2} collisional system by means of the CCSD(T)-F12a/aug-cc-pVQZ level of theory. The interaction energy has been averaged over five \ce{H2} orientations and then fitted as an expansion of angular functions. Finally, state-to-state rate coefficients between the lower hyperfine levels have been computed using recoupling techniques for temperature ranging from 5 to 100 K.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116541

DOI

https://doi.org/10.15278/isms.2022.RH04

Copyright and License Information

Copyright 2022 held by the authors

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