Extended absorption fine structure

Fig. 4. The X-ray Absorption Near Edge Structure (XANES) and the Extended Absorption Fine Structure (EXAFS), — a schematic representation...

X Ray edge and extended absorption fine structure spectra of zinc at the active site are consistent with a seven-coordinate or distorted octahedral environment/ Analysis of the fine structure eliminates sulfur ligands and suggests Zn—N or Zn—O distances of 2.04 and 2.10 A. These are appropriate for an octahedral complex. There is evidence for atoms at distances of 3-4 A from... 

XAS is an interesting tool to obtain in situ results on the near range order of passive layers on metals even for highly disordered or amorphous films. Experimental requirements have been shortly described above. From the reflectivity data, one may calculate with the Fresnel equations the absorption spectra x(E) of the film (see Refs. [140,141] for details). The oscillation of p(E) above the absorption edge, the so-called extended absorption fine structure (EXAFS), leads to the EXAFS fimction %(E) = ( X - MoVMo with the background value Po- The Fourier transform of % E) to the real space yields the structural parameters, i.e., the radius of the coordination shells Rj, their coordination numbers Nj, i.e. the number of neighbors for a given coordination shell and the Debye-Waller factor Oj as a measure of the structural (and thermal) disorder. 

EXAFS Extended X-ray absorption fine structure spectroscopy. A spectroscopic technique which can determine interatomic distances very precisely. 

EXAFS Extended x-ray absorption fine structure [177, 178] Variation of x-ray absorption as a function of x-ray energy beyond an absorption edge the probability is affected by backscattering of the emitted electron from adjacent atoms Number and interatomic distance of surface atoms... 

Lee P A, Citrin P H, Eisenberger P and Kincaid B M 1981 Extended x-ray absorption fine structure—its strengths and limitations as a structural tool Rev. Mod. Rhys. 53 769-806... 

Stdhr J, Kollin E B, Fischer D A, Flastings J B, Zaera F and Sette F 1985 Surface extended x-ray-absorption fine structure of low-Z adsorbates studied with fluorescence detection Rhys. Rev. Lett. 55 1468-71... 

Ingalls R, Crozier E D, Whitmore J E, Seary A J and Tranquada J M 1980 Extended x-ray absorption fine structure of sodium bromide and germanium at high pressure J. Appl. Phys. 51 3158... 

Figure 8.34 Experimental method for extended X-ray absorption fine structure (EXAFS)...

Figure 8.38 Curve fitting of Mo extended X-ray absorption fine structure (EXAFS) for Mo(SC6H4NH)3, taking into account (a) sulphur and (b) sulphur and nitrogen atoms as near neighbours. (Reproduced, with permission, trom Winnick, H. and Doniach, S. (Eds), Synchrotron Radiation Research, p. 436, Plenum, New York, 1980)...

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