Molecular Evolution of H2O:O2 Ices at Different Temperatures in Simulated Space Environments. I. Chemical Kinetics and Equilibrium

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dc.contributor.authorSilva, Josiane Ribeiro Campos
dc.contributor.authorQueiroz, Letícia Marques de Souza Vetrano de
dc.contributor.authorFerrão, Luiz Fernando de Araújo
dc.contributor.authorPilling, Sergio
dc.date.accessioned2025-08-18T14:27:59Z
dc.date.available2025-08-18T14:27:59Z
dc.date.issued22025
dc.description.abstractWe computationally investigated the chemical evolution of H2O:O2 ices (6:1 ratio) under irradiation by cosmic- ray analogs (0.8MeV H+) at 9, 50, and 100K to understand the implications the chemical evolution of O2-containing ices in space, such as the surface of the Moon, comets, outer solar system bodies such Europa and Enceladus, as well as Kuiper Belt objects, and cold regions of the interstellar medium (ISM). Using experimental data and the PROCODA code with 200 reactions coupled equations involving 12 species, we calculated physicochemical parameters such as effective rate coefficients (ERCs), chemical abundances, and desorption. Six species were observed experimentally (H2O, O2, HO2, H2O2, O3, and HO3), while six were predicted but not observed in the experiments (H, H2, H3, O, OH, and H3O). Our findings highlight the influence of temperature on chemical equilibria and desorption yields, with certain reaction rates diminishing at 50 K. Among the results were the lists with the ERCs, and the reaction branching ratio obtained by best-fit models can be employed in astrochemical models. Curiously, we observe that the average ERCs for bimolecular collisions decrease by half as the ice temperature increases, varying from 5.8e-25 to 2.9e-25 cm3 molecules−1 s−1 for the ices studied. These results enhance our understanding of the physical chemistry of astrophysical ices under ionizing radiation, providing valuable data for astrochemical models that assess the effects of cosmic radiation on the composition and stability of icy bodies in the solar system and denser and colder regions of the ISM.
dc.description.physical26 p.
dc.description.sponsorshipCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.uriCNPq (407124/2022-5, 351261/2023-0, 351650/2023-7, 302939/ 2022–9, 302608/2022-2, 316874/2023-0, 163539/2024-3) FAPESP (2024/05115-5) CAPES (88887.919586/2023-00)
dc.format.mimetypePDF
dc.identifier.affiliationInstituto Tecnológico de Aeronáutica
dc.identifier.affiliationUniversidade do Vale do Paraíba
dc.identifier.bibliographicCitationSILVA, J. R. C. et al. Molecular Evolution of H2O:O2 Ices at Different Temperatures in Simulated Space Environments. I. Chemical Kinetics and Equilibrium. Astrophysical Journal, v. 985, n. 2, p. 1-26, 2025. Disponível em: 10.3847/1538-4357/adc924.
dc.identifier.doi10.3847/1538-4357/adc924
dc.identifier.urihttps://repositorio.univap.br/handle/123456789/1026
dc.language.isoen_US
dc.publisherIOP science
dc.rights.holderAstrophysical Journal
dc.subject.keywordAstrochemistry
dc.subject.keywordCosmic rays
dc.subject.keywordMolecular reactions
dc.subject.keywordNatural satellites
dc.titleMolecular Evolution of H2O:O2 Ices at Different Temperatures in Simulated Space Environments. I. Chemical Kinetics and Equilibrium
dc.typeArtigos de Periódicos

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