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Author Zicler, E. ♦ Pauzat, F. ♦ Chaquin, P. ♦ Ellinger, Y. ♦ Bacchus-Montabonel, M. -C.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ COMPUTERIZED SIMULATION ♦ ELECTRIC POTENTIAL ♦ HELIUM ♦ IONIZATION POTENTIAL
Abstract The detection of ArH{sup +} has revived the interest in the search for noble gas containing species. Despite helium being the second most abundant element in the universe (He/H ∼ 1/10), it has never been observed in any other form than that of a neutral/ionized atom in the interstellar medium. Because He is the “most noble” gas, its non-observation as part of neutral molecular systems is understandable. It is more surprising for charged species, especially HeH{sup +} whose spectral signatures are well documented in the laboratory. The purpose of this work was to find a simple positive ion containing He, and likely to be observed as an alternative to undetected HeH{sup +}. Among the HeX{sup 2+} diatomics formed with first row atoms, we focused on X = C because of both its relative abundance and the magnitude of its ionization potentials with respect to He. The formation of CHe{sup 2+} by radiative association is the center of this study. The question was addressed by means of numerical simulations using high level ab initio calculations of the CHe{sup 2+} potential surface, followed by a quantum chemical determination of the rate coefficients for the corresponding radiative association in the range of 10 to 1000K. The radiative association path shows a potential well deep enough to accommodate 20 vibrational levels, and no barrier to oppose the reaction. The rate coefficient varies from ∼4.5 × 10{sup −20} cm{sup 3}s{sup −1} to ∼2.5 × 10{sup −22} cm{sup 3}s{sup −1} for the temperatures considered. The present study suggests that the existence of this species has to be searched for mainly in highly irradiated regions.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-03-21
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 144
Issue Number 11


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