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Exact treatment of beating phenomena in EXAFS

Bauchspieβ, K.R. (1995) Exact treatment of beating phenomena in EXAFS. Physica B: Condensed Matter, 208-209 . pp. 185-186.

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Beating occurs when two coordination shells are closely spaced (δR ≈ 0.1 A ̊). Analyzing two such shells by curve fitting is difficult because the fit parameters exhibit enhanced correlation due to the reduced number of degrees of freedom. Analyzing the combined phase of the two shells in k-space, or its derivative with respect to k, can be performed with a reduced number of fit parameters because only the ratio of the two coordination numbers is required and, with a minor approximation, only the difference of the two EXAFS Debye-Waller factors is needed. Since the beating effect leads to structure that occurs localized in k-space and because this beating structure is usually at the high-k end (for very closely spaced coordination shells) one may neglect the effects of the energy corrections ΔE1 and ΔE2 for the origins of the two k-scales, thus reducing the number of fit parameters by another two. The beating effect can be investigated conveniently by analyzing the derivative of the combined phase of the two coordination shells in k-space. Then the occurrence of beating manifest itself by peaks or dips in the derivative function. This structure, however, can be modified significantly by effects resulting from the Fourier transform. In the present paper such Fourier transform artifacts, the effects of window functions and k-space weighting are taken into account

Publication Type: Journal Article
Murdoch Affiliation: School of Mathematical and Physical Sciences
Publisher: Elsevier B.V.
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