title: Reactivity of xenon with ice at planetary conditions.
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 Xe4O12H12 primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and η-O2, 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.
authors.affiliation: UPMC Univ Paris 06, UMR CNRS 7193, ISTEP, 75005 Paris, France.
authors.forename: Chrystèle
authors.initials: C
authors.lastname: Sanloup
authors.forename: Stanimir A
authors.initials: SA
authors.lastname: Bonev
authors.forename: Majdi
authors.initials: M
authors.lastname: Hochlaf
authors.forename: Helen E
authors.initials: HE
authors.lastname: Maynard-Casely