Applications of H-atom quantum-diffusion reactions in solid para-hydrogen to astrochemical studies: Finding a mysterious link between interstellar isocyanic acid [HNCO] and formamide [H_2NC(O)H]

Haupa, Karolina Anna

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https://hdl.handle.net/2142/104475 Copy

Description

Title

Applications of H-atom quantum-diffusion reactions in solid para-hydrogen to astrochemical studies: Finding a mysterious link between interstellar isocyanic acid [HNCO] and formamide [H_2NC(O)H]

Author(s)

Haupa, Karolina Anna

Contributor(s)

• Lee, Yuan-Pern
• Tarczay, Gyorgy

Issue Date

2019-06-18

Keyword(s)

Astrochemistry and astrobiology in the age of Atacama Large Millimeter/submillimeter Array (ALMA)

Abstract

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.6]{cycle.eps} \end{wrapfigure} Formamide [\chem{H_2NC(O)H}], the smallest molecule containing the biologically important peptide bond, was detected in the interstellar medium (ISM) almost 50 years ago. Recent observations have shown that a strong correlation between its abundance and that of isocyanic acid [\chem{HNCO}] exists in pre- and protostellar environments. It was proposed that this correlation is due to effective synthesis of formamide from \chem{HNCO} by consecutive H-atom addition reactions.\footnote{L\`{o}pez-Sepulcre, \textit{Montly Not. Roy. Astr. Soc.} \textbf{449}, 2438–2458 (2015).} However, Nobel \textit{et al.} showed that bombardment of \chem{HNCO} ice with H atoms led no formation of formamide.\footnote{Nobel, J. A., \textit{et al.}, \textit{Astron. Astrophys.} \textbf{576}, A91 (2015).} So far, no laboratory experiment or theoretical calculations can explain the linkage between these two species.\\ We utilized the advantages of the solid \textit{para-}H$_2$ quantum host to investigate the H-atom reactions linking \chem{HNCO} and formamide. Reactions of \chem{H_2NC(O)H} with H atoms lead to \chem{H_2NCO}, and subsequently \chem{HNCO}. Further hydrogenation reactions convert some HNCO back to \chem{H_2NCO} and \chem{H_2NC(O)H}; the reaction with \chem{D_2NC(O)H} clearly showed that these reactions took place. The correlation between the abundance of \chem{HNCO} and \chem{H_2NC(O)H} can hence be understood by a dual-cycle mechanism shown in the figure, which connects the two species by a quasi-equilibrium. This mechanism and its generalized form for other molecular pairs can also play an important role in the formation of interstellar H$_2$ from H atoms.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/104475

DOI

https://doi.org/10.15278/isms.2019.TA06

Copyright and License Information

Copyright 2019 Karolina Anna Haupa

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