Extended X-ray Absorption Fine Structure (EXAFS) Analysis of Disorder and Multiple-Scattering in Complex Crystalline Solids

• Published in: Journal of the American Chemical Society Vol. 116; no. 7; pp. 2938 - 2949
• Main Authors: O'Day, P. A, Rehr, J. J, Zabinsky, S. I, Brown, G. E. Jr
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.04.1994
• Subjects: 400101 - Activation, Nuclear Reaction, Radiometric & Radiochemical Procedures; 400201 - Chemical & Physicochemical Properties; 990200 - Mathematics & Computers; ALKALINE EARTH METAL COMPOUNDS; BACKSCATTERING; CALCIUM COMPOUNDS; COBALT COMPOUNDS; COHERENT SCATTERING; COMPUTERIZED SIMULATION; CRYSTALLOGRAPHY; DATA; DEBYE-WALLER FACTOR; DIFFRACTION; EXPERIMENTAL DATA; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; INFORMATION; INORGANIC COMPOUNDS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NICKEL COMPOUNDS; NUMERICAL DATA; OXYGEN COMPOUNDS; SCATTERING; SILICATES; SILICON COMPOUNDS; SIMULATION; THEORETICAL DATA; TRANSITION ELEMENT COMPOUNDS; X-RAY DIFFRACTION
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00086a026

Quantitative determination of local atomic structure in complex materials using extended X-ray absorption fine structure (EXAFS) analysis was tested on eight inorganic compounds of known structure, including natural and synthetic crystalline solids, at ambient conditions. Our aim was to test the accuracy of experimental and theoretical EXAFS standard functions in determining the number of backscattering atoms (N) at a distance (R) beyond the ligating shell of the central absorber atom where effects from disorder, multiple-scattering, and overlapping shells of atoms may significantly influence the EXAFS spectra. These compounds have complicated structures compared to metals and contain Fe, Co, or Ni as the central absorbing atom and mixtures of second-row (C,O,F), third-row (Si, Cl), and fourth-row (Ca, Fe, Co, Ni) atoms as backscatters. Comparison of results using both experimental phase shift and amplitude functions (derived from the EXAFS spectra of the compounds) and those calculated from ab initio theory (using the computer code FEFF 5) shows that interatomic distances for single-scattering paths among metal atoms can be determined to within 0.02 A of values determined independently by X-ray diffraction up to a distance of 4 A from the central absorber by either method. 25 refs., 7 figs., 6 tabs.