Astrochemically relevant H-atom-abstraction and H-atom-addition reactions connecting fulminic acid (HCNO) and formaldoxime (H2CNOH)

ABSTRACT While fulminic acid (HCNO) is a well-known interstellar molecule, its partially hydrogenated form, formaldoxime (H2CNOH), has not been detected yet in the interstellar medium (ISM). A possible reason for the non-detection of H2CNOH can be that in the presence of H atoms the quasi-equilibriu...

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Veröffentlicht in:Monthly notices of the Royal Astronomical Society 2023-05, Vol.521 (2), p.2649-2660
Hauptverfasser: Keresztes, Barbara, Góbi, Sándor, Csonka, István Pál, Ragupathy, Gopi, Bazsó, Gábor, Tarczay, György
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Sprache:eng
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Zusammenfassung:ABSTRACT While fulminic acid (HCNO) is a well-known interstellar molecule, its partially hydrogenated form, formaldoxime (H2CNOH), has not been detected yet in the interstellar medium (ISM). A possible reason for the non-detection of H2CNOH can be that in the presence of H atoms the quasi-equilibrium between these species is shifted towards HCNO. To support this hypothesis, the H-atom-abstraction and H-atom-addition reactions of HCNO and H2CNOH were investigated in solid para-H2 matrix at 3.1 K. The reactions were followed by IR spectroscopy. The experiments proved that both the H-atom-addition reaction to HCNO and the H-atom-abstraction reaction from H2CNOH proceed at low temperatures, and these reactions yield H2CNO radical. In addition, H-atom-addition reaction can also take place with H2CNOH, leading to the formation of H3CNOH radical. Both H2CNO and H3CNOH radicals can react with H atoms, either in a H-atom-addition reaction or in a H-atom-abstraction reaction. Although all of these reactions are barrierless, experimentally the H-atom-addition reactions were not observed, revealing that the H-atom-abstraction reactions of these radicals are more effective. Therefore, in the case of a quasi-equilibrium condition, the abundance of H2CNOH in the ISM is expected to be lower than that of HCNO. Furthermore, the results also indicate that the H-atom-addition and H-atom-abstraction reactions between H2CNOH and HCNO can act as catalytic cycles for interstellar H2 formation.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stad710