Applications of X-ray Absorption Spectroscopy in Heterogeneous Catalysis: EXAFS, Atomic XAFS, and Delta XANES

The sections in this article are Introduction Physical Principles of X-Ray Adsorption and Electron Scattering Absorption of X-Rays Scattering of the Photoelectron Isolating the Oscillatory Part (χAX + χEX) from the Absorption Data Pre-Edge Subtraction and Determination of Eedge Post-Edge Background Removal and Normalization EXAFS The EXAFS Equation EXAFS Data Analysis Fourier Transformation Fourier Filtering Phase Shifts and Backscattering Amplitudes Derived from EXAFS Data Obtained from Reference Compounds Obtaining R, N and Δσ2, k-Space and R-Space Fitting The Use of Theoretical References Difference File Technique Structural Analysis with EXAFS of a Heterogeneous Single-Site Cr/SiO2 Ethylene Trimerization Catalyst. An Illustrative Example Introduction Raw XAS Data of New Cr/SiO2 Catalysts and CrCl3–TAC Reference Compound Fabrication and Calibration of Ab Initio Phase Shifts and Backscattering Amplitudes EXAFS Data Analysis Conclusions: EXAFS Data Analysis Atomic XAFS (AXAFS) Introduction Physical Principles of AXAFS The Field and Inductive Interactions Separation of AXAFS from EXAFS Data The Interatomic Potential Model for Metal–Support Interaction ΔXANES Technique Introduction Calculations of Pt L3 ΔXANES Using the FEFF8 Code Experimental ΔXANES Data from Pt/H-USY and Pt/NaY Experimental Information ΔXANES Spectra Relevance for Pt-Catalyzed Hydrogenolysis/Hydrogenation Reactions General Applicability of the ΔXANES Technique Acknowledgments Keywords: physical principles of XAS; EXAFS data-analysis; atomic XAFS; delta XANES