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Determination of the Ortho to Para Ratio of H_2Cl^+ and H_2O^+ from Submillimeter Observations

Gerin, Maryvonne and De Luca, Massimo and Lis, Dariusz C. and Kramer, Carsten and Navarro, Santiago and Neufeld, David and Indriolo, Nick and Godard, Benjamin and Le Petit, Franck and Peng, Ruisheng and Phillips, Thomas G. and Roueff, Evelyne (2013) Determination of the Ortho to Para Ratio of H_2Cl^+ and H_2O^+ from Submillimeter Observations. Journal of Physical Chemistry A, 117 (39). pp. 10018-10026. ISSN 1089-5639. doi:10.1021/jp4004533.

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The opening of the submillimeter sky with the Herschel Space Observatory has led to the detection of new interstellar molecular ions, H_2O^+, H_2Cl^+, and HCl^+, which are important intermediates in the synthesis of water vapor and hydrogen chloride. In this paper, we report new observations of H_2O^+ and H_2Cl^+ performed with both Herschel and ground-based telescopes, to determine the abundances of their ortho and para forms separately and derive the ortho-to-para ratio. At the achieved signal-to-noise ratio, the observations are consistent with an ortho-to-para ratios of 3 for both H_2O^+ and H_2Cl^+, in all velocity components detected along the lines-of-sight to the massive star-forming regions W31C and W49N. We discuss the mechanisms that contribute to establishing the observed ortho-to-para ratio and point to the need for a better understanding of chemical reactions, which are important for establishing the H_2O^+ and H_2Cl^+ ortho-to-para ratios.

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Lis, Dariusz C.0000-0002-0500-4700
Indriolo, Nick0000-0001-8533-6440
Roueff, Evelyne0000-0002-4949-8562
Additional Information:© 2013 American Chemical Society. Received: January 15, 2013. Revised: July 19, 2013. Publication Date (Web): July 19, 2013. This work could not have been prepared without the pioneering and inspiring work by Oka, both for his fundamental spectroscopy work and for his more recent involvement in astronomy, with the beautiful detection of the H_3^+ ion. We thank the anonymous referee for his/her comments that help to significantly improve this paper. This material is based upon work at the Caltech Submillimeter Observatory, which is operated by the California Institute of Technology under cooperative agreement with the National Science Foundation (AST-0838261). HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada, and the United States (NASA) under the leadership of SRON, Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France, and the U.S. Consortium members: (Canada) CSA, U. Waterloo; (France) CESR, LAB, LERMA, IRAM; (Germany) KOSMA, MPIfR, MPS; (Ireland) NUI Maynooth; (Italy) ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri-INAF; (Netherlands) SRON, TUD; (Poland) CAMK, CBK; (Spain) Observatorio Astronomico Nacional (IGN), Centro de Astrobiologia; (Sweden) Chalmers University of Technology - MC2, RSS & GARD, Onsala Space Observatory, Swedish National Space Board, Stockholm University - Stockholm Observatory; (Switzerland) ETH Zurich, FHNW; (USA) CalTech, JPL, NHSC. M.G., E.R., and B.G. acknowledge the support from the Centre National de Recherche Spatiale (CNES) and the SCHISM project (ANR-09-BLAN-0231). The authors declare no competing financial interest.
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Centre National de Recherche Spatiale (CNES)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-09-BLAN-0231-01
Issue or Number:39
Record Number:CaltechAUTHORS:20131209-115208994
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Official Citation: Determination of the Ortho to Para Ratio of H2Cl+ and H2O+ from Submillimeter Observations Maryvonne Gerin, Massimo de Luca, Dariusz C. Lis, Carsten Kramer, Santiago Navarro, David Neufeld, Nick Indriolo, Benjamin Godard, Franck Le Petit, Ruisheng Peng, Thomas G. Phillips, and Evelyne Roueff The Journal of Physical Chemistry A 2013 117 (39), 10018-10026
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42899
Deposited By: Ruth Sustaita
Deposited On:09 Dec 2013 20:22
Last Modified:10 Nov 2021 16:30

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