EXAFS extended X-ray adsorption fine

Elder, R.C., Tepperman, K.G., Eidsness, M.K., Heeg, M.J., Shaw, C.F. Ill and Schaeffer, N. A. (1983) Gold-based antiarthritic drugs and metabolites. Extended x-ray adsorption fine structure (EXAFS) spectroscopy and x-ray absorption near edge spectroscopy (XANES). ACS Symposium Series, 209, 385-400. 

The Cu adsorbate structure was studied using STM and EXAFS (extended x-ray absorption fine structure) techniques, but it is not yet well understood. UPD-OPD transition is in the range —82 to —71 mV. Bulk fee Cu spacing is reached after deposition of about lOCu monolayers. Holzle et al. (72) have shown that UPD Cu deposition on Au(l 11) is a combined adsorption-nucleation and growth process. 

A number of different experimental methods are available to observe fine structure. In extended x-ray adsorption fine structure (EXAFS) experiments x-ray photons excite core levels and the cross section is determined by x-ray absorption... 

ESCA (electron spectroscopy for chemical analysis) = XF(E)S ESR = electron spin resonance Euler s theorem 1.2.28, 1.2.14a evanescent waves 1.7.75, 1.18, 2.54 EXAFS = extended X-ray absorption fine structure exchange (adsorption from binary mixtures) 2.1, 2.3, 2.4 constant (2.3.16]... 

Direct in situ extended X-ray adsorption fine structure (EXAFS) measurements) from synchrotron radiation (14-18) permit the determination of species adsorbed to neighboring ions and to central ions on oxide surfaces in the presence of water. Such investigations showed, for example, that selenite is bound in an inner-sphere complex and selenate is bound in an outer-sphere complex to the central Fe(III) ions of a goethite surface. This technique also showed that Pb(II) is bound in an inner-sphere complex to 8-Al203 (19) and that Cr(III) is bound in an inner-sphere complex at the oxide-water interface of Mn(IV) oxides and ferric hydrous oxides (17, 18). 

Metallic sites Temperature-programmed reduction (TPR) X-ray adsorption near-edge spectroscopy (XANES) Extended X-ray adsorption fine structure (EXAFS) Mossbauer spectroscopy X-ray photoelectron spectroscopy (XPS) Electron paramagnetic spectroscopy (EPR)... 

NEXAFS is generally characterized by spectral features near to an X-ray absorption edge and contains information about the electronic and structural properties of the adsorbing atom. This is distinct from the extended X-ray adsorption fine structure (EXAFS), which is typically observed in the region 50-1000eV above an... 

Extended X-ray absorption fine structure (EXAFS) spectrum Part of an X-ray absorption spectrum that is used to identify the coordination of atoms, estimate bond lengths, and determine the adsorption complexes on the surfaces of adsorbents. EXAFS spectra may provide useful information on the speciation (valence state), surface complexes, and the coordination of arsenic on adsorbents (e.g. (Randall, Sherman and Ragnarsdottir, 2001 Ladeira, et al. (2001) Teixeira and Ciminelli (2005) Kober, et al. (2005)) (compare with X-ray absorption spectroscopy (XAS), X-ray absorption near edge structure (XANES) spectra, and X-ray absorption fine structure spectroscopy (XAFS)). 

X-ray absorption spectroscopy (XAS) Methods that use X-rays to investigate the physical and chemical properties of materials on an atomic scale. XAS includes X-ray adsorption fine structure (XAFS) spectroscopy and its X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. 

The development of modem surface science techniques over the past decade has allowed for the investigation of numerous properties of adsorption at the atomic level. These techniques offer information about the electrode surface and the molecular identity of the species adsorbed at the electrode surface. These techniques have been used to study the electrode surface however, many require a gas phase or ex situ environment as summarized in Table 1. XAS including the two complimentary parts, x-ray absorption near edge stracture (XANES) and extended x-ray absorption fine stmc-ture (EXAFS) are in situ/operando spectroscopic techniques that can provide unique site-specific adsorbate bonding and particle size information. Further, these techniques do not suffer from the adsorption by the bulk electrolyte such as in the IR region. X-ray Diffraction (XRD) of course also provides detailed stractural... 

The intent of this chapter is not to survey noninvasive surface spectroscopy but to illustrate briefly how it is applied to resolve the Stummian issue of whether inner-sphere surface complexes form. For this purpose, the application of electron spin resonance (ESR), electron nuclear double resonance (ENDOR), and electron spin echo envelope modulation (ESEEM) spectroscopies to elucidate metal cation speciation and the use of extended X-ray absorption fine structure (EXAFS) spectroscopy to detect surface anion species will be described. Emphasis will be on the interpretation of spectra. Sample preparation and instrumentation details were reviewed in recent volumes edited by Hawthorne (55) and Perry (27). Because the constant capacitance model was developed in the context of adsorption by hydrous oxides, these... 

According to the structure and composition of materials and analysis requirements of the researcher, the following analysis techniques can be selected for the characterization of mesoporous materials XRD, TEM, adsorption-desorption (N2 or other gas), solid MAS NMR (29Si, 27Al, 13C, etc.), scanning electron microscopy (SEM), catalysis test, Fourier Transform infra-red (FT-IR), thermal analysis, UV-visible, and chemical analysis. IR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure XANES, extended X-ray absorption fine structure EXAFS and other spectral methods are commonly used to analyse metal elements such as Ti in the mesoporous material frameworks. 

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