Energy partitioning in H2 formation on interstellar carbonaceous grains. Insights from ab initio molecular dynamics simulations
Jubert, Léana (Universitat Autònoma de Barcelona. Departament de Química)
Martínez-Bachs, Berta (Universitat Autònoma de Barcelona. Departament de Química)
Pareras Niell, Gerard (Universitat Autònoma de Barcelona. Departament de Química)
Rimola Gibert, Albert (Universitat Autònoma de Barcelona. Departament de Química)

Data:	2025
Resum:	Molecular hydrogen (H) stands as the most abundant molecule within the interstellar medium (ISM), primarily originating from the coupling of two H atoms on the surfaces of dust grains. The role of dust grains during the H formation is of third bodies, dissipating the nascent reaction energy and thereby stabilizing the newly formed molecule and preventing it from dissociating back. Whether the formed H remains adsorbed or not on the surface (in this latter case undergoing chemical desorption, CD) largely depends on the type of grain and its capability to absorb the reaction energy excess. In diffuse interstellar clouds, dust grains are typically bare and are composed primarily of silicates or carbonaceous materials, while in denser regions they are covered in ices mostly of water. While water-ice-covered grains have been elucidated to be efficient third bodies, the behavior of carbonaceous grains is still unknown. In this study, ab initio molecular dynamics (AIMD) simulations are employed to analyze how the reaction energy is distributed between the newly formed H and a large graphene slab, as a model of carbonaceous grains in diffuse clouds, and assess the feasibility of CD. The results indicate that only a fraction of the reaction energy is absorbed by the surface, leaving the newly formed H with sufficient internal energy for CD to occur.
Ajuts:	European Commission 865657 Agencia Estatal de Investigación PID2021-126427NB-I00 Agencia Estatal de Investigación CNS2023-144902 European Commission 101105235
Nota:	Altres ajuts: acords transformatius de la UAB
Drets:	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, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Physical Chemistry Chemical Physics, Vol. 27, Issue 29 (August 2025) , p. 15385-15397, ISSN 1463-9076

DOI: 10.1039/d5cp01585e
PMID: 40620133

13 p, 1.8 MB

El registre apareix a les col·leccions:
Articles > Articles de recerca
Articles > Articles publicats