X-ray absorption spectroscopy EXAFS

Mazurek M, Benker N, Roth C, Buhrmester T, Fuess H. 2006. Electrochemical impedance and X-ray absorption spectroscopy (EXAFS) as in situ methods to study PEMFC anode. Fuel Cells 6 16-20. 

Tingle, T.N., Waychunas, G.A., Bird, D.K. and O Day, P. (1996) X-ray absorption spectroscopy (EXAFS) of arsenic solid solution in pyrite, Clio Mine, Mother Lode gold district, Tuolumne County. Abstracts with Programs. The Geological Society of America, 28(7), 518. 

Keywords Synchrotron Radiation, X-ray absorption spectroscopy, EXAFS,... 

Despite numerous investigations of Grignard compounds, almost no information exists about intra- and interatomic distances of these reagents in solution. This is not necessarily remarkable, since the methods of physical chemistry discussed in the previous section are of course not able to provide such information. But X-ray absorption spectroscopy (EXAFS) and largo angle X-rav scattering (LAXS) can. 

A very detailed high resolution electron microscopy (HREM) study, together with X-ray absorption spectroscopy (EXAFS) was performed on LaCo5, Co/La2C>3 and... 

This is a study of the non-convergent ordering of Mg and Ni in synthetic olivines by means of the neutron powder diffraction and X-ray absorption spectroscopy (EXAFS). The implications of the intracristalline ordering to olivine crystal chemistry and their application to the consideration of thermodynamic relations, geothermometry, geo-speedometry, and minor or trace element distribution control is discussed in detail. 

Co = Catechol oxidase He = Hemocyanin Tyr = Tyrosinase MePy2 = Al,Al-bis(2-pyridylethyl)methylamine TACN = 1,3,5-triazocyclononane TMPA = Tris[(2-pyridyl) methyl]amine XYL-0 = a, a -bis[Al,Al-bis(2-pyridylethyl) amino]-m-xylene-2-olate XYL = a, a -bis[Al,Al-bis(2-pyri-dylethyl)amino]-m-xylene XYL-R = Meta substituted a,a bis[Al,Al-bis(2-pyridylethyl)amino]-m-xylene N3 = N, N, Al, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-propane-1,2-diamine N4 = Al,Al,Al, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-butane-1,2-diamine N5 = Al,A,lV, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-pentane-1,2-diamine HB(3,5-Pr2pz)3 = Hydrotris(3, 5-diisopropyl-l-pyrazolyl) borate XAS = X-ray absorption spectroscopy EXAFS = Extended X-ray absorption fine structure rR = resonance Raman. 

Heald SM, Tranquada JM (1990) X-ray absorption spectroscopy EXAFS and XANES. In Rossiter BW, Hamilton JF (eds) Physical methods of chemistry, vol V. Determination of structural features of crystalline and amorphous solids, 2nd edn. Wiley, New York, p 189... 

For XANES, a narrow energy range (< 50 eV) close to the absorption edge is studied. However, for extended X-ray absorption spectroscopy (EXAFS) the spectrum is acquired at energies much further from the absorption edge. Information... 

Another technique that makes use of the tuneability of SR sources is x-ray absorption spectroscopy (xas) (2). This is relatively rarely used in pol5uner research. One of the few examples found in the literature deals with halato-telechelic ionomers (40). These are short linear chains selectively terminated by a metal car-boxylate or sulfonate ionic group. The local order of these groups could be determined by using extended x-ray absorption spectroscopy (exafs). More work using this technique applied to ionomer morphology is reported (41). 

Important contributions come from the application of X-ray absorption spectroscopy (EXAFS/XANES). Comparing the XANES spectra of dehydrated TS-1 with those of several model compounds, Behrens et al. concluded that TS-1 contains tetrahedral, square pyramidal and octahedral Ti, in the approximate ratio 10 15 75 [57,58] the same authors did not exclude that at ambient conditions all the Ti atoms assume the octahedral coordination [57]. However, these results are affected by the poor quality of the TS-1 sample used, probably containing the majority of the Ti in extra-framework positions, as indicated by the reported value of the unit cell volume (lower than that of the pure silica parent structure) [57,58]. 

In spite of the fairly long history since the discovery and isolation of these enzymes, little has been known on the structure and the catalytic mechanism. The active center of the enzyme is known to be a high-spin Fe +, that has made limited progress in the study of the structure and mechanism due to the spectroscopic inaccessibility. Recently, studies on magnetic circular dichroism (MCD) [128] and X-ray absorption spectroscopy (EXAFS and XANES) [129-132] have brought about some progress in understanding the structures and mechanisms of these enzymes. 

The particle size of Pd and Pt phases encapsulated in zeolite hosts can be controlled by chosing appropriate reduction conditions for the ion exchanged, dehydrated precursor form.27 28.29 Based on x-ray diffraction studies, a bidisperse distribution of Pd particles appears to be typical In addition to particles 10-20 A in size, a second Pd phase was assigned to Pd atoms in the cage systems. In the following we describe the synthesis and characterization of Pd ensembles, consisting of 2 to 4 correlated atcnns, which are stabilized at room temperature in an open, chemically accessible zeolite matrix. Characterization of the clusters was done by means of x-ray absorption spectroscopy (EXAFS). ... 

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