Is Missing Xenon in the Earth's Inner Core?

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Is Missing Xenon in the Earth's Inner Core?

Postby David Entwistle » Sun Oct 06, 2013 5:47 pm

Is Missing Xenon in the Earth's Inner Core?

Li Zhu, Hanyu Liu, Guangtian Zou, Yanming Ma

http://arxiv.org/abs/1309.2169

Atmospheric studies of Earth have shown that more than 90% of xenon (Xe) is depleted if compared to the abundance of chondritic meteorites. This missing Xe paradox remains a long-standing mystery and has become an extensive debate2-18. Earlier high pressure experimental and theoretical studies that were unable to find the reaction of Xe with iron (Fe), the main constituent of the Earth's inner core, seemingly excluded the Earth's inner core from the Xe reservoir. Here we report the first evidence on the chemical reaction of Xe with Fe at conditions of Earth's inner core predicted through our developed first-principles structure searching technique unbiased by any known structural knowledge. We find that Xe and Fe form stable inter-metallic compound of XeFe3 stoichiometry by adopting a Cu3Au-type cubic structure. By virtue of an unusual Xe -> Fe charge transfer, Xe loses its chemical inertness by opening up the completed filled 5p electron shell and thereby functions as a 5p-like element, while Fe is negatively charged acting as an oxidant rather than a reductant as usual. Our work establishes that the Earth's inner core is the natural reservoir for storage of Xe, and possibly provides the key to unlock the missing Xe paradox.
David Entwistle
 
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