Reactivity of Xenon with Ice at Planetary Conditions.

UPMC Univ Paris 06, UMR CNRS 7193, ISTEP, 75005 Paris, France.
Physical Review Letters (Impact Factor: 7.73). 06/2013; 110(26):265501. DOI: 10.1103/PhysRevLett.110.265501
Source: PubMed

ABSTRACT We report results from high pressure and temperature experiments that provide evidence for the reactivity of xenon with water ice at pressures above 50 GPa and a temperature of 1500 K-conditions that are found in the interiors of Uranus and Neptune. The x-ray data are sufficient to determine a hexagonal lattice with four Xe atoms per unit cell and several possible distributions of O atoms. The measurements are supplemented with ab initio calculations, on the basis of which a crystallographic structure with a Xe_{4}O_{12}H_{12} primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and η-O_{2}, and has the same oxygen subnetwork as the latter. Furthermore, it has a weakly metallic character and likely undergoes sublattice melting of the H subsystem. Our findings indicate that Xe is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth.

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