Journal Article high-energy X-rays total scattering Research Support, Non-U.S. Gov't X-ray diffraction X-ray total scattering catalytic reactors charge density elastic stiffness heterogeneous catalysis high angular resolution in situ X-ray scattering normal equations operando profile measurements powder X-ray diffraction powder diffraction single-crystal diffuse scattering small-angle scattering solvothermal chemistry structure–activity relationships synchrotron powder diffraction thermal diffuse scattering thiourea time-resolved experiments