Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-759-C2-760
DOI: 10.1051/jp4:1997228

Co-Refinement of Diffraction Anomalous Fine-Structure Data

M. Newville¹, J.O. Cross², B. Ravel³, L.B. Sorensen³, C.E. Bouldin⁴ and Y. Yacoby<sup>5

1</sup>  Lawrence Livermore National Laboratory, L-219, Livermore CA 94550, U.S.A.
²  Naval Research Laboratory, Code 6680, Washington DC 20375, U.S.A.
³  Department of Physics, Box 351560, University of Washington, Seattle, WA 98195, U.S.A.
⁴  National Institute of Standards and Technology, Gaithersburg MD 20899, U.S.A.
⁵  Racah Institute of Physics, Hebrew University, Jerusalem, Israel

Abstract
Diffraction Anomalous Fine-Structure (DAFS) combines the sensitivity to long-range-order of diffraction with the short-range-order sensitivity of XAFS. This makes it possible to use a set of DAFS measured intensities to simultaneously refine both long- and short-range structural parameters, while maintaining some constraints between them. This method combines a calculation of the structure factor based on the unit cell of the crystal with a calculation of the fine-structure X(E) around each resonant site. Tabulated values of the scattering amplitude are used away from the resonant energies, while the near-edge anomalous scattering amplitude is calculated for the resonant sites using a differential Kramers-Krönig transform of an embedded atom absorption coefficient µ₀(E) from FEFF. We discuss some of the subtleties of this approach to DAFS analysis.

© EDP Sciences 1997