High-pressure structures of the hydrates of noble gases

Gas hydrates, in which hydrogen-bonded crystalline water frameworks encage gas atoms or molecules, have been extensively studied at low pressure in both fundamental and applied science. Hydrate of natural gas occurs on the sea floor and is a potential energy source as well as a source of greenhouse gas. Hydrates of astrophysically relevant gases are candidate components for the interiors of the icy bodies of the outer Solar system. We propose to explore the stability and structure of the hydrates of He, Ne, Ar, and Kr at pressures up to 100 GPa by x-ray powder diffraction in diamond anvil cell. Based on published calculations and by analogy with the high-pressure behaviour of CH4 hydrate, we expect to find that these systems form new high-pressure structures and are stable at much higher pressures than presently believed.