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Title	en Methane Formation Efficiency on Icy Grains: Role of Adsorption States
Creator	en Tsuge, Masashi NRID 1000060454211 en Molpeceres, Germán en Aikawa, Yuri en Watanabe, Naoki NRID 1000050271531
Accessrights	metadata only access
Rights	https://creativecommons.org/licenses/by/4.0/ en Creative Commons Attribution 4.0 International
Subject	NDC 440
Description	Abstract en Methane (CH4) is one of the major components of the icy mantle of cosmic dust prevalent in cold, dense regions of interstellar media, playing an important role in the synthesis of complex organic molecules and prebiotic molecules. Solid CH4 is considered to be formed via the successive hydrogenation of C atoms accreting onto dust: C + 4H → CH4. However, most astrochemical models assume this reaction on the ice mantles of dust to be barrierless and efficient, without considering the states of adsorption. Recently, we found that C atoms exist in either the physisorbed or chemisorbed state on compact amorphous solid water, which is analogous to an interstellar ice mantle. These distinct adsorption states considerably affect the hydrogenation reactivity of the C atom. Herein, we elucidate the reactivities of physisorbed and chemisorbed C atoms with H atoms via sequential deposition and codeposition processes. The results indicate that only physisorbed C atoms can produce CH4 on ice. Combining this finding with a previous estimate for the fraction of physisorbed C atoms on ice, we determined the upper limit for the conversion of C atoms into CH4 to be 30%.
Publisher	en American Astronomical Society
Date	Issued2024-09-20
Language	und
Resource Type	journal article
Version Type	NA
Identifier	HDL http://hdl.handle.net/2115/93086
Relation	isIdenticalTo DOI https://doi.org/10.3847/1538-4357/ad656a
Journal	PISSN 0004-637X EISSN 1538-4357 en The Astrophysical Journal Volume Number973 Issue Number2 Page Start80
Oaidate	2024-09-28