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Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C₆H₆

Cooke, Ilsa R. and Gupta, Divita and Messinger, Joseph P. and Sims, Ian R. (2020) Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C₆H₆. Astrophysical Journal Letters, 891 (2). Art. No. L41. ISSN 2041-8213. https://resolver.caltech.edu/CaltechAUTHORS:20200316-150528419

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Abstract

The low-temperature reaction between CN and benzene (C₆H₆) is of significant interest in the astrochemical community due to the recent detection of benzonitrile, the first aromatic molecule identified in the interstellar medium (ISM) using radio astronomy. Benzonitrile is suggested to be a low-temperature proxy for benzene, one of the simplest aromatic molecules, which may be a precursor to polycyclic aromatic hydrocarbons. In order to assess the robustness of benzonitrile as a proxy for benzene, low-temperature kinetics measurements are required to confirm whether the reaction remains rapid at the low gas temperatures found in cold dense clouds. Here, we study the C₆H₆ + CN reaction in the temperature range 15–295 K, using the well-established CRESU technique (a French acronym standing for Reaction Kinetics in Uniform Supersonic Flow) combined with pulsed-laser photolysis-laser-induced fluorescence. We obtain rate coefficients, k(T), in the range (3.6–5.4) × 10⁻¹⁰ cm³ s⁻¹ with no obvious temperature dependence between 15 and 295 K, confirming that the CN + C₆H₆ reaction remains rapid at temperatures relevant to the cold ISM.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/2041-8213/ab7a9cDOIArticle
https://arxiv.org/abs/2003.02101arXivDiscussion Paper
ORCID:
AuthorORCID
Cooke, Ilsa R.0000-0002-0850-7426
Gupta, Divita0000-0002-6639-4909
Messinger, Joseph P.0000-0001-7305-3945
Sims, Ian R.0000-0001-7870-1585
Additional Information:© 2020. The American Astronomical Society. Received 2020 January 23; revised 2020 February 27; accepted 2020 February 27; published 2020 March 16. The authors thank Jonathan Courbe, Jonathan Thiévin, Didier Biet, Ewen Gallou, and Alexandre Dapp for technical support. The authors thank Brett McGuire, Christopher Shingledecker, and Mitchio Okumura for helpful discussions. J.P.M. was supported by the National Science Foundation Graduate Research Fellowship (NSF GRFP) and the National Science Foundation Graduate Research Opportunities Worldwide (NSF GROW) programs. J.P.M. would also like to thank the Office for Science and Technology of the Embassy of France in the United States for a Chateaubriand Fellowship. The authors acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement 695724-CRESUCHIRP and under the Marie Skłodowska-Curie grant agreement 845165-MIRAGE. The authors are also grateful for support from the European Regional Development Fund, the Region of Brittany and Rennes Metropole. This work was supported by the French National Programme "Physique et Chimie du Milieu Interstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES. Software: SciPy (Virtanen et al. 2019), NumPy (van der Walt et al. 2011), Matplotlib (Hunter 2007), StatsModels (http://www.statsmodels.org).
Funders:
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Embassy of FranceUNSPECIFIED
European Research Council (ERC)695724
Marie Curie Fellowship845165
European Regional Development FundUNSPECIFIED
Region of Brittany and Rennes MetropoleUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Institut National du Patrimoine (INP)UNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Subject Keywords:Reaction rates ; Astrochemistry ; Interstellar molecules ; Interstellar medium ; Interdisciplinary astronomy ; Polycyclic aromatic hydrocarbons ; Dense interstellar clouds ; Interstellar clouds
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Reaction rates (2081); Astrochemistry (75); Interstellar molecules (849); Interstellar medium (847); Interdisciplinary astronomy (804); Polycyclic aromatic hydrocarbons (1280); Dense interstellar clouds (371); Interst
Record Number:CaltechAUTHORS:20200316-150528419
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200316-150528419
Official Citation:Ilsa R. Cooke et al 2020 ApJL 891 L41
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101926
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:17 Mar 2020 15:04
Last Modified:17 Mar 2020 15:04

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