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Trapping of noble gases in proton-irradiated silicate smokesWe have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.
Document ID
19930041157
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Nichols, R. H., Jr.
(Washington Univ. Saint Louis, MO, United States)
Nuth, J. A., III
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hohenberg, C. M.
(Washington Univ. Saint Louis, MO, United States)
Olinger, C. T.
(Los Alamos National Lab. NM, United States)
Moore, M. H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1992
Publication Information
Publication: Meteoritics
Volume: 27
Issue: 5
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
93A25154
Funding Number(s)
CONTRACT_GRANT: NGT-59854
CONTRACT_GRANT: NAG9-7
CONTRACT_GRANT: NGT-50194
Distribution Limits
Public
Copyright
Other

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