Analysis of experimental extended x-ray-absorption fine-structure (EXAFS) data using calculated curved-wave, multiple-scattering EXAFS spectra

Jose Mustre, Yizhak Yacoby, Edward A. Stern, John J. Rehr

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75 Scopus citations

Abstract

We present an EXAFS analysis method that is accurate and generally applicable and can be implemented on a fast microcomputer within a reasonable amount of computation time. The analysis is based on the comparison between a calculated EXAFS spectrum of a parametrized model with the experimental spectrum and the refinement of the model parameters. The calculated EXAFS spectrum is evaluated taking into account the curved-wave nature of the photoelectron and multiple scattering up to and including third-order collinear scattering. Such an expansion treats accurately all multiple-scattering contributions that contribute to the Fourier transform of the EXAFS spectrum up to the fourth-neighbor distance. The comparison between theory and experiment is thus limited to this distance. In this calculation we schematically express the contributions of the various scattering configurations in the form 0=F(k)sin[kL+(k)] and expand to lowest order the amplitude F and the phase functions in terms of all structural and potential parameters. This expansion is quite accurate and significantly speeds up the computation. We discuss a set of parameters which seems to account for the limitations in the employed theory, providing a very good fit between theory and experiment. The analysis method and the parameters have been implemented successfully on a number of systems. We present here the analysis of the copper EXAFS spectrum. The experimental data contain 20 independent experimental points; yet we obtain a very good fit with only six parameters. The results also show the importance of both double and triple collinear scattering as well as the importance of noncollinear double scattering.

Original languageEnglish
Pages (from-to)10843-10851
Number of pages9
JournalPhysical Review B
Volume42
Issue number17
DOIs
StatePublished - 1990
Externally publishedYes

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