Journal Article total scattering CO oxidation Pd(100) Research Support, Non-U.S. Gov't X-ray diffraction catalytic reactors diamond anvil cell extreme conditions heterogeneous catalysis high-energy X-rays high-energy surface X-ray diffraction (HESXRD) high-pressure melting of iron in situ X-ray scattering operando profile measurements planar laser-induced fluorescence (PLIF) powder X-ray diffraction pulse laser heating ray-tracing simulations single-crystal diffuse scattering small-angle scattering solvothermal chemistry structure–activity relationships