Novel rhenium gasket design for nuclear resonant inelastic x-ray scattering at high pressure.

For the first time, a highly absorbing element, rhenium, has been proven to be a strong, reliable, and safe gasket material for achieving high pressure in nuclear resonant inelastic x-ray scattering (NRIXS) experiments. Rhenium foil was cut into rectangular slices and in order to reduce absorption, the elevated imprint due to preindenting of the gasket is removed using electrical discharge machining. By utilizing this novel gasket design, transmission losses were mitigated while performing NRIXS experiments conducted on the 119Sn and 57Fe Mössbauer isotopes.

Phonon density of states of metallic Sn at high pressure.

Determination of the lattice dynamics of Sn at high pressure has represented a major experimental challenge and eluded previous attempts. Here we report the first successful measurement of the phonon density of states of Sn at high pressure to 64 GPa using nuclear resonant inelastic x-ray scattering. We also present density functional theory calculations that are in excellent agreement with the measured data. The results of this combined experimental and theoretical study establish reliable phonon density of states of Sn at high pressure. It makes possible an accurate description of its thermodynamic properties that are of great importance and interest in high pressure research.