Measuring Dynamic Properties of Warm Dense Matter with High-Resolution Inelastic X-ray Scattering

Warm dense matter (WDM) is a complex state of matter where strong ion-ion coupling combined with the quantum behavior of the electron fluid make simulation and modeling challenging; experimental verification in this regime is essential. X-ray scattering experiments, which utilize high-intensity beams of penetrating radiation to probe the micro-structure and dynamics, allow for critical testing of our simulations. I will provide an overview of our high-resolution (∼50 meV) X-ray scattering platform, designed for use with free-electron lasers, with a resolution capable of measuring the quasi-elastic Rayleigh peak (in the non-collective regime) and discerning ion modes (in the collective regime). In the first case, we have directly measured the electron-ion equilibration rate in various laser-excited metallic thin films (Au, Ag, Cu, and Ti). In the latter, we have successfully measured the sound speed in warm dense methane.