Rotational Spectra of Interstellar N- and CN-PAHs: Pyrene and Coronene

By Keith Cowing
Press Release
November 4, 2022
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Rotational Spectra of Interstellar N- and CN-PAHs: Pyrene and Coronene
Calculated rotational spectra of the considered N- and CN-PAHs at 10 K (green), 100 K (red) and 300 K (blue).

The detection of benzonitrile (C6H5CN), 1- and 2-cyano-naphthalene (C10H7CN) in the cold, dark molecular cloud TMC-1 at centimetre (cm) wavelengths has opened up prospects for the detection of other N- and CN-containing polycyclic aromatic hydrocarbons (PAHs).

In this light, the pure rotational spectra of N-pyrene (C15H9N), CN-pyrene (C15H9CN), N-coronene (C23H11N) and CN-coronene (C23H11CN) are reported here for the first time. The B3LYP/6-311+G(d,p) level of theory, in the Density Functional Theory (DFT) calculations, achieves the best performance for calculating the spectroscopic parameters and simulating the rotational spectra.

The large permanent dipole moment of CN-PAHs makes them the most suitable PAH species for detection in the interstellar medium. Additionally, pyrene’s smaller partition function makes CN-pyrene a prime candidate to be discovered in cold, dark molecular clouds such as the TMC-1. The present work sets a benchmark for theoretical rotational spectra of N- and CN-containing PAHs and may act as a guide for laboratory experiments and observational searches.

Akant Vats, Amit Pathak

Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2211.01636 [astro-ph.GA] (or arXiv:2211.01636v1 [astro-ph.GA] for this version)
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Submission history
From: Akant Vats
[v1] Thu, 3 Nov 2022 07:57:54 UTC (437 KB)
Astrobiology, Astrochemistry

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻