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Laboratory IR Studies and Astrophysical Implications of C2H2-Containing Binary IcesStudies of molecular hot cores and protostellar environments have shown that the observed abundance of gas-phase acetylene (C2H2) cannot be matched by chemical models without the inclusion of C2H2 molecules subliming from icy grain mantles. Searches for infrared (IR) spectral features of solid-phase acetylene are under way, but few laboratory reference spectra of C2H2 in icy mixtures, which are needed for spectral fits to observational data, have been published. Here, we report a systematic study of the IR spectra of condensed-phase pure acetylene and acetylene in ices dominated by carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and water (H2O). We present new spectral data for these ices, including band positions and intrinsic band strengths. For each ice mixture and concentration, we also explore the dependence of acetylene's nu5-band position (743 cm-1, 13.46 micrometers) and FWHM on temperature. Our results show that the nu5 feature is much more cleanly resolved in ices dominated by non-polar and low-polarity molecules, specifically CO, CO2, and CH4, than in mixtures dominated by H2O-ice. We compare our laboratory ice spectra with observations of a quiescent region in Serpens.
Document ID
20120007588
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Knez, C.
(Maryland Univ. College Park, MD, United States)
Moore, M.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Ferrante, R.
(Naval Academy Annapolis, MD, United States)
Hudson, R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
April 1, 2012
Publication Information
Publication: The Astrophysical Journal
Volume: 748
Issue: 2
ISSN: 0004-4637x
Subject Category
Astrophysics
Distribution Limits
Public
Copyright
Other

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