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Dynamic molecular oxygen production in cometary comae

Yao, Yunxi and Giapis, Konstantinos P. (2017) Dynamic molecular oxygen production in cometary comae. Nature Communications, 8 . Art. No. 15298. ISSN 2041-1723. PMCID PMC5424151.

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Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov–Gerasimenko. Its origin was ascribed to primordial gaseous O_2 incorporated into the nucleus during the comet’s formation. This thesis was put forward after discounting several O_2 production mechanisms in comets, including photolysis and radiolysis of water, solar wind–surface interactions and gas-phase collisions. Here we report an original Eley–Rideal reaction mechanism, which permits direct O_2 formation in single collisions of energetic water ions with oxidized cometary surface analogues. The reaction proceeds by H_2O+ abstracting a surface O-atom, then forming an excited precursor state, which dissociates to produce O_2−. Subsequent photo-detachment leads to molecular O_2, whose presence in the coma may thus be linked directly to water molecules and their interaction with the solar wind. This abiotic O_2 production mechanism is consistent with reported trends in the 67P coma and raises awareness of the role of energetic negative ions in comets.

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URLURL TypeDescription CentralArticle
Yao, Yunxi0000-0002-0814-6675
Giapis, Konstantinos P.0000-0002-7393-298X
Additional Information:© 2017 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit Received: 18 November 2016; Accepted: 07 March 2017; Published online: 08 May 2017. This report was based on work funded by the National Science Foundation/Department of Energy Partnership for Basic Plasma Science and Engineering (Award No. 1202567). Author Contributions: Y.Y. and K.P.G. designed the experiments and co-wrote the paper. Y.Y. conducted experimental measurements. K.P.G. supervised the project. The authors declare no competing financial interests.
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PubMed Central ID:PMC5424151
Record Number:CaltechAUTHORS:20170505-180434414
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Official Citation:Yao, Y. & Giapis, K. P. Dynamic molecular oxygen production in cometary comae. Nat. Commun. 8, 15298 doi: 10.1038/ncomms15298 (2017)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77245
Deposited By: George Porter
Deposited On:08 May 2017 18:22
Last Modified:03 Oct 2019 17:55

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