![Chemical structure of the aromatic nitriles cyanobenzene, d5-cyanobenzene, 1,2-dicyanobenzene, 1,3- dicyanobenzene and 1,4-dicyanobenzene -- [astro-ph.SR]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Infrared.png?fit=1200%2C670&ssl=1)
[astro-ph.SR] Motivated by recent detections of several aromatic nitriles in Taurus Molecular Cloud-1, we report laboratory and theoretical investigations of the vibrational spectroscopy and photochemistry of singly and doubly cyano-substituted benzene in solid para-hydrogen matrices.
We compare the photochemistry of cyanobenzene (benzonitrile) and three dicyanobenzene isomers initiated by excitations at 193 nm. In addition, we report the photochemistry of deuterated cyanobenzene (d5-cyanobenzene), enabling us to determine the major products produced during the cyanobenzene photodissociation.
The major products observed in the photolysis of all the nitriles are HCN and HNC, which are likely produced by hydrogen abstraction from para-H2 by the CN radical. This indicates that the major photodissociation channel involves cleavage of the bond between the ring and the nitrile group, forming the phenyl (or cyanophenyl) radical + CN.
We observe secondary photoproducts similar to those found during benzene photolysis. Our findings may aid the interpretation of recent JWST mid-infrared observations of aromatics in photodissociation regions.
Sam McGrath, Vincent J. Esposito, Linshan Zeng, Thomas H. Speak, Brendan Moore, Pavle Djuricanin, Jun Miyazaki, Takamasa Momose, Ilsa R. Cooke
Comments: Accepted for publication in The Astrophysical Journal
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Materials Science (cond-mat.mtrl-sci)
Cite as: arXiv:2608.09889 [astro-ph.SR](or arXiv:2608.09889v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2608.09889
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Submission history
From: Ilsa Cooke
[v1] Mon, 10 Aug 2026 17:39:38 UTC (775 KB)
https://arxiv.org/abs/2608.09889
Astrobiology, AStrochemistry,
