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Continuous Cauchy wavelet transform analyses of EXAFS spectra; a qualitative approach

Manuel Munoz, Pierre Argoul and Francois Farges
Continuous Cauchy wavelet transform analyses of EXAFS spectra; a qualitative approach
American Mineralogist (April 2003) 88 (4): 694-700

Abstract

To better understand the extended X-ray absorption fine structure (EXAFS) spectroscopic information obtained for complex materials such as those encountered in Earth materials, we propose to use the Continuous Cauchy Wavelet Transform (CCWT). Thanks to this method, EXAFS spectra can be visualized in three dimensions: the wavevector (k), the interatomic distance uncorrected for phase-shifts (R'), and the CCWT modulus (corresponding to the continuous decomposition of the EXAFS amplitude terms). Consequently, more straightforward qualitative interpretations of EXAFS spectra can be performed, even when spectral artifacts are present, such as multiple-scattering features, multi-electronic excitations, or noise. More particularly, this method provides important information concerning the k range of each EXAFS contribution, such as next nearest-neighbors identification. To illustrate the potential of CCWT analyses applied to EXAFS spectra, we present experimental and theoretical spectra obtained for thorite and zircon at the Th L (sub II) and Zr K edges, respectively. Then, we present CCWT analyses of EXAFS spectra collected for amorphous materials of geochemical and environmental interest, including sodium trisilicate glass and an aqueous chloride solution, at the Mo K and Au L (sub III) edges, respectively. Further studies based on CCWT phase terms are underway, in order to quantitatively characterize anharmonic information from EXAFS contributions.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 88
Serial Issue: 4
Title: Continuous Cauchy wavelet transform analyses of EXAFS spectra; a qualitative approach
Affiliation: Universite de Marne-La-Vallee, Laboratoire des Geomateriaux, Marne-La-Vallee, France
Pages: 694-700
Published: 200304
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 40
Accession Number: 2003-053384
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Secondary Affiliation: Unite Mixte ENPC-LCPC, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200317
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