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Author Bergantini, Alexandre ♦ Maksyutenko, Pavlo ♦ Kaiser, Ralf I.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ABSORPTION SPECTROSCOPY ♦ BRANCHING RATIO ♦ COSMIC RADIATION ♦ ETHANE ♦ ETHANOL ♦ HYDROXIDES ♦ ICE ♦ INFRARED SPECTRA ♦ INTERSTELLAR GRAINS ♦ ISOMERS ♦ MASS ♦ MASS SPECTROSCOPY ♦ METHANOL ♦ METHYL ETHER ♦ MOLECULES ♦ PHOTOIONIZATION ♦ RECOMBINATION ♦ SIMULATION ♦ STARS ♦ TAIL ELECTRONS
Abstract The structural isomers ethanol (CH{sub 3}CH{sub 2}OH) and dimethyl ether (CH{sub 3}OCH{sub 3}) were detected in several low-, intermediate-, and high-mass star-forming regions, including Sgr B2, Orion, and W33A, with the relative abundance ratios of ethanol/dimethyl ether varying from about 0.03 to 3.4. Until now, no experimental data regarding the formation mechanisms and branching ratios of these two species in laboratory simulation experiments could be provided. Here, we exploit tunable photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) to detect and analyze the production of complex organic molecules (COMs) resulting from the exposure of water/methane (H{sub 2}O/CH{sub 4}) ices to energetic electrons. The main goal is to understand the formation mechanisms in star-forming regions of two C{sub 2}H{sub 6}O isomers: ethanol (CH{sub 3}CH{sub 2}OH) and dimethyl ether (CH{sub 3}OCH{sub 3}). The results show that the experimental branching ratios favor the synthesis of ethanol versus dimethyl ether (31 ± 11:1). This finding diverges from the abundances observed toward most star-forming regions, suggesting that production routes on interstellar grains to form dimethyl ether might be missing; alternatively, ethanol can be overproduced in the present simulation experiments, such as via radical–radical recombination pathways involving ethyl and hydroxyl radicals. Finally, the PI-ReTOF-MS data suggest the formation of methylacetylene (C{sub 3}H{sub 4}), ketene (CH{sub 2}CO), propene (C{sub 3}H{sub 6}), vinyl alcohol (CH{sub 2}CHOH), acetaldehyde (CH{sub 3}CHO), and methyl hydroperoxide (CH{sub 3}OOH), in addition to ethane (C{sub 2}H{sub 6}), methanol (CH{sub 3}OH), and CO{sub 2} detected from infrared spectroscopy. The yield of all the confirmed species is also determined.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-06-01
Publisher Place United States
Journal Astrophysical Journal
Volume Number 841
Issue Number 2


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