Astrochemistry

Machine-learning Identified Molecular Fragments Responsible For Infrared Emission Features Of Polycyclic Aromatic Hydrocarbons

By Keith Cowing
Status Report
astro-ph.GA
July 18, 2023
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Machine-learning Identified Molecular Fragments Responsible For Infrared Emission Features Of Polycyclic Aromatic Hydrocarbons
Schematic of the processes for generating the ECFP of 1-Naphthaldehyde. Arrows in colors indicate the correlation between molecular fragments and IR bands. The purple circle corresponds to the fragment center, the yellow circle represents aromatic atoms, and the asterisk symbol represents adjacent atoms. The atomic number is indicated by the digit following the colon. The gray chemical bonds depict the adjacent portion of the fragments. — astro-ph.GA

Machine learning feature importance calculations are used to determine the molecular substructures that are responsible for mid and far-infrared (IR) emission features of neutral polycyclic aromatic hydrocarbons (PAHs).

Using the extended-connectivity fingerprint as a descriptor of chemical structure, a random forest model is trained on the spectra of 14,124 PAHs to evaluate the importance of 10,632 molecular fragments for each band within the range of 2.761 to 1172.745 microns.

The accuracy of the results is confirmed by comparing them with previously studied unidentified infrared emission (UIE) bands. The results are summarized in two tables available as Supplementary Data, which can be used as a reference for assessing possible UIE carriers.

We demonstrate that the tables can be used to explore the relation between the PAH structure and the spectra by discussing about the IR features of nitrogen-containing PAHs and super-hydrogenated PAHs.

Zhisen Meng, Yong Zhang, Enwei Liang, Zhao Wang

Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2307.08277 [astro-ph.GA] (or arXiv:2307.08277v1 [astro-ph.GA] for this version)
Journal reference: MNRAS 525, L29-L35 (2023)
Related DOI:
https://doi.org/10.1093/mnrasl/slad089
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Submission history
From: Zhao Wang
[v1] Mon, 17 Jul 2023 06:57:42 UTC (1,633 KB)
https://arxiv.org/abs/2307.08277
Astrobiology, Astrochemistry

Keith Cowing

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) 🖖🏻

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