Radiation-driven Destruction of N-heterocycles in H₂O-ice mixtures

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Citation of Original Publication

Tribbett, Patrick, Yukiko Yarnall, Reggie Hudson, Perry Gerakines, and Christopher Materese. 2025. "Radiation-Driven Destruction Of N-Heterocycles in H₂O-Ice Mixtures" Paper presented at EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 10 September, 2025. https://doi.org/10.5194/epsc-dps2025-172.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

Simple nitrogen (N-) heterocycles are expected to be an abundant class of molecules within the interstellar medium (ISM). Computational and laboratory studies have demonstrated previously that these molecules likely form during the polymerization of acetylene in the presence of hydrogen cyanide (Ricca et al. 2001, Hamid et al. 2014), a process expected to occur in the stellar outflows of carbon-rich AGB stars. This production pathway is analogous to the formation of benzene, which has been detected in the presence of polyacetylenic chains (Cernicharo et al. 2001). Additionally, laboratory studies have demonstrated that N-heterocycles readily form during the irradiation of icy materials. Specifically, Materese et al. 2015 identified pyridine and isoquinoline in the room-temperature residues formed from photolyzed and warmed ices containing water, ammonia, and benzene or naphthalene. More recently, Wang et al. 2024 identified pyrrole and indole in electron-irradiated acetylene and ammonia ice mixtures.