Journal ArticleDOI
Anisotropic x-ray absorption in layered compounds
Steve M. Heald,Edward A. Stern +1 more
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TLDR
In this paper, a study of anisotropy effects in x-ray absorption in the layered compounds of layered compounds was presented, and the theoretical expression for the EXAFS anisotropic at the edges was explicitly displayed.Abstract:
A study is presented of anisotropy effects in x-ray absorption in the layered compounds of $2H\ensuremath{-}\mathrm{W}{\mathrm{Se}}_{2}$ and $1T\ensuremath{-}\mathrm{T}\mathrm{a}{\mathrm{S}}_{2}$. In the measurements it was essential to separate the thickness effect from the true anisotropy effect which is dependent on the angle between the x-ray polarization and the crystal axes. The Se $K$ edge and the W and Ta $L$ edges were measured. Anisotropy in the white line of Se was found but no anisotropy was discerned in the W and Ta white lines. It is pointed out that x-ray absorption in general, and the extended x-ray absorption fine structure (EXAFS) in particular, have the anisotropy dependence of a second-order tensor and the theoretical expression for the EXAFS anisotropy at the ${L}_{2,3}$ edges is explicitly displayed. The anisotropy of the EXAFS in the Se and W absorption was measured and a good agreement with theory is found. The anisotropy of EXAFS at the ${L}_{2,3}$ edges has the new feature of a cross term between the final $s$ and $d$ states, which permits a determination from the measurements that the average contributions of the final $s$ state is 0.02 of that of the final $d$ states to the total absorption of the W ${L}_{3}$ edge. Finally, only qualitative agreement is obtained between band calculations and the near edge x-ray absorption structure, as expected theoretically.read more
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Journal ArticleDOI
Extended x-ray absorption fine structure—its strengths and limitations as a structural tool
TL;DR: In this article, the authors review the development of extended x-ray absorption fine structure (EXAFS) within the last decade and discuss selected examples of applications of EXAFS chosen to illustrate both the strength and limitations of this structural tool.
Journal ArticleDOI
Study of the L 23 edges in the 3 d transition metals and their oxides by electron-energy-loss spectroscopy with comparisons to theory
TL;DR: In this article, a variation from the statistical white-line intensity ratio of 2:1 has been observed across the $3d$ transition row, with values ranging between 0.8:1 for Ti to 5: 1 for FeO. It is suggested that the anomalous ratios may be explained by a breakdown of the exchange mechanism caused by an exchange mechanism.
Journal ArticleDOI
Electron-yield saturation effects in L-edge x-ray magnetic circular dichroism spectra of Fe, Co, and Ni
TL;DR: In this paper, it was shown that errors in the extracted orbital moment values due to saturation effects can be in excess of 100% and even yield the wrong sign for films as thin as 50 \AA{}.
Journal ArticleDOI
Angular dependence of X-ray absorption spectra
TL;DR: In this article, a detailed account of the dependence of X-ray absorption spectra (XAS) on polarisation and light beam directions is given, using a spherical tensor expansion of the absorption cross section.
Journal ArticleDOI
Quantitative zn speciation in smelter-contaminated soils by exafs spectroscopy
Alain Manceau,Bruno Lanson,Michel L. Schlegel,Jean Claude Harge,Martine Musso,Laurent Eybert-Bérard,Jean-Louis Hazemann,Daniel Chateigner,Geraldine M. Lamble +8 more
TL;DR: In this article, a combination of X-ray diffraction, texture goniomom- etry, and powder and polarized extended Xray absorption fine structure (EXAFS) spectra were used to investigate quantitatively the speciation of Zn in soils contaminated by three smelters.
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