Optical Spectroscopies – within our static high-pressure laboratories at WSU, we are using micro-Raman, emission, absorption, and Impulse Stimulated Light Scattering (ISLS). Raman measures the molecular excitations of the samples and will show abrupt changes at transitions related to phase changes, charge transfer, and dissociation. Broadband absorption and emission spectroscopies, which probe electronic properties, have been used to determine Drude-like metallic behavior of extended solids. ISLS measures the sound wave speed in liquid, which can be used for determining the elastic constants of single crystal solids as well as any remnant of phase changes in liquids, at high pressures.
X-Ray Diffraction and Spectroscopy Using the capabilities that the PI has developed as an institutional partner at HPCAT/APS and other 3rd generation synchrotron sources, a range of new diagnostic techniques is now possible. Many of the low-Z materials proposed in the present study are all poor x-ray scatterer and the brightness of the third-generation source is crucial for obtaining measurable powder-diffraction scattering intensities. Conventional x-ray diffraction combined with simultaneous heating (resistive and laser) will be used to measure lattice constants in solids and, using recently published methods, the structure and density in liquids. New inelastic x-ray techniques, such as nonresonance and resonance XRS with high energy-resolution 1-0.1 eV enable us to measure x-ray absorption of low-Z and other materials in a DAC. Such data demonstrate changes in electronic states across the types of molecular-to-nonmolecular transitions studied in the present study.