Simple Molecular Solids at Ultrahigh Pressures

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9972750HemleyThe goal of this project is the systematic experimental study of pressure-induced transformations of simple molecular materials to static ultrahigh pressures above 300 GPa (3 megabars) using recently developed diamond-anvil cell techniques. The experiments focus on pressure-induced transformations in representative systems such as H2, H2O, CH4, N2, O2, S, rare gases, and dense molecular compounds formed from these materials, as well as in simple metals such as Li and Na. New single-crystal, polycrystalline, and radial x-ray methods are used to determine crystal structures above 100 GPa in these systems. Vibrational and electronic properties will be measured by optical, synchrotron infrared, and Raman spectroscopy in order to extend the phase diagrams, examine quantum and other dynamical effects, and to determine the stability limit of the different molecular forms. New highly sensitive magnetic susceptibility and resistivity methods allow measurements of superconductivity and identification of other transformations to novel states of electronic and magnetic order to 200-300 GPa in these materials. Finally, the pressure range of techniques used to investigate dense materials under static conditions will be extended. %%%The goal of this project is the systematic experimental study of pressure-induced transformations of simple molecular materials to ultrahigh pressures above 300 GPa (3 megabars). The experiments focus on pressure-induced transformations in representative systems such as H2, H2O, CH4, N2, O2, S, rare gases, and dense molecular compounds formed from these materials, as well as in simple metals such as Li and Na. Vibrational and electronic properties will be measured in order to extend the phase diagrams, examine quantum and other dynamical effects, and to determine the stability limit of different molecular forms. New highly sensitive magnetic susceptibility and resistivity methods allow measurements of superconductivity and identification of other transformations to novel states of electronic and magnetic order in the 200-300 GPa pressure range.***