Radiation-induced transformations of matrix-isolated ethanol molecules at cryogenic temperatures: a FTIR study

Zasimov, P.V.; Sanochkina, E.V.; Tyurin, D.A.; Feldman, V.I.

Авторы: Zasimov Pavel V., Sanochkina Elizaveta V., Tyurin Daniil A., Feldman Vladimir I.
Журнал: Physical Chemistry Chemical Physics
Том: 25
Номер: 33
Год издания: 2023
Издательство: Royal Society of Chemistry
Местоположение издательства: United Kingdom
Первая страница: 21883
Последняя страница: 21896
DOI: 10.1039/d3cp02834h
Аннотация: Ethanol (C2H5OH) is the second important alcohol molecule in various space media (molecular clouds, star formation regions and, highly likely, interstellar ices), where it can be exposed to light and ionizing radiation leading to complex organic molecules (COMs) and eventually to the biologically important species. In order to better understand the radiation-induced evolution of ethanol molecules in icy media, we have examined the transformations of isolated C2H5OH and C2D5OH under the action of X-rays and vacuum ultraviolet (VUV) radiation in solid inert matrices (Ne, Ar, Kr and Xe) at 4.4 K using the Fourier transform infrared (FTIR) spectroscopy. The results obtained with X-ray irradiation demonstrate the formation of a variety of radiolysis products corresponding to dehydrogenation (CH3CHOH•, CH3CHO, CH2CHOH, CH3CO•, H2CCO–H2, H2CCO, HCCO•, CCO) and C–C bond rupture (H2CO, HCO•, CO, CH4, and CH3•). The absorptions of CH3CHOH• radical related to the CCO stretching (the bands at 1249.1, 1247.0, 1246.2, and 1245.1 cm–1, in Ne, Ar, Kr and Xe, respectively) were first tentatively characterized on the basis of comparison with available computational data. In addition, the C2H2∙∙∙H2O complex was found, which corresponds to dehydrogenation followed by the C–O bond cleavage. The results were confirmed by experiments with isotopic substitution. It was found that dehydrogenation strongly predominated in a xenon matrix, while the skeleton bond rupture is more feasible in neon and argon. The matrix effect was attributed to a significant role of “hot” reaction channels in neon and argon, which are efficiently quenched due to relaxation in more polarizable xenon. The VUV photolysis (185 nm) in Ar and Xe matrices yields a similar set of products, except for CH3CHOH• and CH2CHOH, which were not found (the non-observation of the former species may be explained by its efficient secondary photolysis). The plausible mechanisms of product formation and astrochemical implications of the results are discussed.
Добавил в систему: Засимов Павел Валерьевич

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Radiation-induced transformations of matrix-isolated ethanol molecules at cryogenic temperatures: a FTIR studyстатья

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