Issue 24, 2000
From the journal:

Physical Chemistry Chemical Physics

An Hermite expansion method for EXAFS data treatment and its application to Fe K-edge spectra

Andrey S. Krylov,a   Janet F. Poliakoffb  and  Michael Stockenhuber*c  

* Corresponding authors

a Faculty of Computational Mathematics and Cybernetics, Moscow Lomonoso State Uniersity (MSU), Vorobiey Gory, Moscow, Russia
E-mail: kryl@cs.msu.su
Fax: + 7 (0)95 939 2596
Tel: + 7 (0)95 939 5336

b Department of Computing, The Nottingham Trent Uniersity (TNTU), Burton Street, Nottingham, UK
E-mail: Janet.Poliakoff@ntu.ac.uk
Fax: + 44 (0)115 848 6518
Tel: + 44 (0)115 848 2864

c Department of Chemistry and Physics, Catalysis Research Laboratory, The Nottingham Trent Uniersity (TNTU), Clifton Lane, Nottingham, UK
E-mail: Michael.Stockenhuber@ntu.ac.uk
Fax: + 44 (0)115 948 6694
Tel: + 44 (0)115 948 6694

Abstract

A new Hermite expansion method has been developed for EXAFS data treatment. This transformation technique involves an expansion into a series of odd Hermite functions, which are eigenfunctions of the sine Fourier transform. In this communication, we report mainly the use of the method to filter iron K-edge X-ray absorption data. Unlike the other numerical Fourier techniques, the new method takes into consideration additional physical information on the experimental data, i.e. both the length of the interval of the measurements and an estimation of the length of the interval of significant structure changes in real space are parameters of the method. The method was validated with iron K-edge fluorescence spectra of magnetite and applied to iron exchanged ZSM-5 zeolite with low iron loadings (0.75 wt.%). We are able to show that, compared to the same data unfiltered or spectra Fourier filtered with a large Gaussian window, the noise level is strongly reduced and artefacts at higher distances disappear. The validity of the method was proved by applying it to magnetite (Fe3O4), where it is possible to fit the two Fe–O distances (octahedral and tetrahedral sites) known from X-ray diffraction. With the new method, these shells are statistically significant and are observed as individual contributions in the Fourier transforms. We also show that the new method, unlike conventional Fourier techniques, retains the statistical independence of the data.

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Article information

DOI
https://doi.org/10.1039/B004346J
Article type
Paper
Submitted
30 May 2000
Accepted
30 Oct 2000
First published
23 Nov 2000

Phys. Chem. Chem. Phys., 2000,2, 5743-5749

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An Hermite expansion method for EXAFS data treatment and its application to Fe K-edge spectra

A. S. Krylov, J. F. Poliakoff and M. Stockenhuber, Phys. Chem. Chem. Phys., 2000, 2, 5743 DOI: 10.1039/B004346J

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