Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds

Stockett, Mark H., Bull, James N. ORCID: https://orcid.org/0000-0003-0953-1716, Cederquist, Henrik, Indrajith, Suvasthika, Ji, MingChao, Navarro Navarrete, José E., Schmidt, Henning T., Zettergren, Henning and Zhu, Boxing (2023) Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds. Nature Communications, 14. ISSN 2041-1723

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After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and kinetic energy release distributions produced from an ensemble of internally excited 1-CNN+ studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence – radiative relaxation via thermally populated electronic excited states – efficiently stabilizes 1-CNN+, owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.

Item Type: Article
Additional Information: Acknowledgements: This work was supported by Swedish Research Council grant numbers 2016-03675 (MHS), 2018-04092 (HTS), 2019-04379 (HC), 2020-03437 (HZ), Knut and Alice Wallenberg Foundation grant number 2018.0028 (HC, HTS, and HZ), Olle Engkvist Foundation grant number 200-575 (MHS), and Swedish Foundation for International Collaboration in Research and Higher Education (STINT) grant number PT2017-7328 (JNB and MHS). We acknowledge the DESIREE infrastructure for provisioning of facilities and experimental support, and thank the operators and technical staff for their invaluable assistance. The DESIREE infrastructure receives funding from the Swedish Research Council under the grant numbers 2017-00621 and 2021-00155. This article is based upon work from COST Action CA18212 - Molecular Dynamics in the GAS phase (MD-GAS), supported by COST (European Cooperation in Science and Technology).
Uncontrolled Keywords: chemistry(all),biochemistry, genetics and molecular biology(all),general,physics and astronomy(all) ,/dk/atira/pure/subjectarea/asjc/1600
Faculty \ School: Faculty of Science > School of Chemistry
UEA Research Groups: Faculty of Science > Research Groups > Chemistry of Light and Energy
Faculty of Science > Research Groups > Centre for Photonics and Quantum Science
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Depositing User: LivePure Connector
Date Deposited: 25 Jan 2023 10:30
Last Modified: 09 Feb 2023 13:51
URI: https://ueaeprints.uea.ac.uk/id/eprint/90795
DOI: 10.1038/s41467-023-36092-0

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