Pair Distribution Function Analysis of High-Energy X-ray Scattering Data

Pair distribution function (PDF) analysis is an emerging structure characterization tool with the potential to provide valuable new insights into a broad range of problems in heterogeneous catalysis. The method yields atomic scale structural information with crystallographic resolution, without the need for crystalline order implicit in conventional Bragg diffraction analysis. Accordingly, it can be used to study the nanoscale and/or defect-rich materials systems often involved in heterogeneous catalysis. In many ways, the structural information available from a PDF measurement is analogous to insights from extended X-ray absorption fine structure (EXAFS), diffraction, and small-angle X-ray scattering (SAXS) studies. The PDF is obtained experimentally from a scattering measurement. The highly penetrating nature of the high-energy X-rays allows versatility in the materials and design of the sample environment for in-situ studies. Determining the interaction or binding of molecules at the active surface of a catalyst is important in understanding the catalytic mechanism.