Gas-Phase vs. Grain-Surface Formation of Interstellar Complex Organic Molecules : A Comprehensive Quantum-Chemical Study
Martínez-Bachs, Berta (Universitat Autònoma de Barcelona. Departament de Química)
Rimola, Albert (Universitat Autònoma de Barcelona. Departament de Química)

Fecha:	2023
Resumen:	Several organic chemical compounds (the so-called interstellar complex organic molecules, iCOMs) have been identified in the interstellar medium (ISM). Examples of iCOMs are formamide (HCONH), acetaldehyde (CHCHO), methyl formate (CHOCHO), or formic acid (HCOOH). iCOMs can serve as precursors of other organic molecules of enhanced complexity, and hence they are key species in chemical evolution in the ISM. The formation of iCOMs is still a subject of a vivid debate, in which gas-phase or grain-surface syntheses have been postulated. In this study, we investigate the grain-surface-formation pathways for the four above-mentioned iCOMs by transferring their primary gas-phase synthetic routes onto water ice surfaces. Our objective is twofold: (i) to identify potential grain-surface-reaction mechanisms leading to the formation of these iCOMs, and (ii) to decipher either parallelisms or disparities between the gas-phase and the grain-surface reactions. Results obtained indicate that the presence of the icy surface modifies the energetic features of the reactions compared to the gas-phase scenario, by increasing some of the energy barriers. Therefore, the investigated gas-phase mechanisms seem unlikely to occur on the icy grains, highlighting the distinctiveness between the gas-phase and the grain-surface chemistry.
Ayudas:	European Commission 865657 Agencia Estatal de Investigación PID2021-126427NB-I00
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Astrochemistry ; Interstellar grains ; Water ice surfaces ; Molecule formation ; Icoms ; Computational chemistry
Publicado en:	International journal of molecular sciences, Vol. 24, Num. 23 (November 2023) , art. 16824, ISSN 1422-0067

DOI: 10.3390/ijms242316824
PMID: 38069147

25 p, 4.6 MB

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