Benchmarking Astrochemistry Paradigms: Relative Absence of C6H5CN+ in the Diffuse ISM

The detectability of C₆H₅CN⁺ (benzonitrile cation) in the diffuse ISM is re-evaluated. A holistic evidentiary framework suggests C₆H₅CN⁺ is relatively absent in the diffuse ISM owing to the following concurrently: a marginal intramolecular vibrational energy redistribution (IVR) favoring fragmentation, recurrent fluorescence being an improbable mechanism in this case to prevent dissociation, mismatches between observed DIBs and experimental results, and the hitherto absence of DIBs matching any similarly sized cations.

The putative gap in bottom-up synthesis is reaffirmed (diffuse ISM), and although DIB sources are largely unknown, within a broader approach the lines can help benchmark astrochemistry paradigms.

The results relied on new advantageous Daly et al. experimental spectra, an expanded observational DIB analysis (APO catalog), and complementary ωB97X-D/cc-pVTZ computations.

Daniel Majaess, Cercis Morera-Boado, Tina A. Harriott, Quazi Rahi, Halis Seuret, Lou Massa, Cherif F. Matta

Comments: To appear in publication
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2603.23739 [astro-ph.GA](or arXiv:2603.23739v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2603.23739
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Submission history
From: Daniel Majaess
[v1] Tue, 24 Mar 2026 21:50:53 UTC (160 KB)
https://arxiv.org/abs/2603.23739

Astrobiology, Astrochemistry,