Extended X-ray absorption fine structure Fourier transform

Electric Field Induced Second Harmonic Extended Huckel Molecular Orbital Electron Spin Echo Envelope Modulation Extended X-ray Absorption Fine Structure Fourier-Transform-ESR hexamethylphosphoric acid triamide Magnetic Circular Dichroism mesityl... 

Figure 8.39 Fourier transformed Fe extended X-ray absorption fine structure (EXAFS) and retransformation, after applying a 0.9-3.5 A filter window, of (a) a rubredoxin, (b) a plant ferredoxin and (c) a bacterial ferredoxin, whose structures are also shown. (Reproduced, with permission, Ifom Teo, B. K. and Joy, D. C. (Eds), EXAFS Spectroscopy, p. 15, Plenum, New York, 1981)...

In the present study, we synthesized in zeolite cavities Co-Mo binary sulfide clusters by using Co and Mo carbonyls and characterized the clusters by extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and high resolution electron microscopy (HREM). The mechanism of catalytic synergy generation in HDS is discussed. 

Final justification for using terms such as inner- or outer-sphere awaits direct spectroscopic confirmation. Electron Spin Resonance, Mossbauer, and Fourier Transform Infrared-Cylindrical Internal Reflection Spectroscopic techniques are being used to establish the structure of surface complexes (see, e.g., McBride, Ambe et al., and Zeltner et al., this volume). The potential for using EXAFS (extended x-ray absorption fine structure) to establish the type of surface complex for Pb + adsorbing onto goethite is currently being undertaken in our laboratory. 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

Using various amines added to the ammonia bath (in most cases with added hydrazine), sphalerite ZnS fihns were obtained with a crystal size of ca. 3 nm [ 118]. Rutherford Backscattering Spectroscopy (RBS) analyses showed that there was about twice as much Zn in the fihns as S. (More basic solution and more hydrazine gave more stoichiometric films). Extended X-ray Absorption Fine Structure (EX-AFS) and Fourier Transform Infra-red (EUR) spectroscopy showed that the fihns did not have Zn-0 groups but rather Zn-OH ones [122] and that there is probably a mixture of ZnS and unreacted Zn(OH)2, quite likely as a ZnS shell around a Zn(OH)2 core. Optical spectra gave a bandgap of ca. 3.85 eV, considerably blue-shifted from the bulk value of 3.6 eV, as expected from such small crystals. 

First qualitative analyses of the Fourier transformations (FTs) of the respective EXAFS (extended X-ray absorption fine structure) oscillations of the reference compounds (figure 6) show peaks up to 5.5 A while the incorporated transition metal oxides A and B show only peaks up to 3.3 A. A comparison of the first shell (oxygen shell) between 1 and 2 A shows no difference in the magnitude for the reference CoFe2C>4 and the products A and B. In contrast, the higher shells, which represent the metal-metal distances, are strongly reduced for the products A and B compared to the bulk reference compounds, which is another indication for small particles within the pores. Further quantitative EXAFS analyses are currently in progress. 

Particle diameter Inductively coupled plasma-optical emission spectrometry (ICP-OES) Fourier transform infrared spectrometry Mass spectrometry X-ray fluorescence Extended X-ray absorption fine structure (EXAFS) spectroscopy X-ray absorption near edge (XANES) spectroscopy Static and dynamic laser light scattering Scanning probe technologies... 

Abbreviations BCC. body centered cubic DOS. density of states ESR. electron spin resonance HX.AI S, extended X-ray absorption fine structure F CC. face centered cubic (a crystal structure). FID, free induction decay FT, Fourier transform FWHM, full width at half maximum HCP, hexagonal close packed HOMO, highest occupied molecular orbital IR, Infrared or infrared spectroscopy LDOS, local density of states LUMO, lowest unoccupied molecular orbital MAS. magic angle spinning NMR. nuclear magnetic resonance PVP. poly(vinyl pyrrolidone) RF. Radiofrequency RT, room temperature SEDOR, spin echo double resonance Sf, sedor fraction SMSI, strong metal-support interaction TEM. transmission electron microscopy TOSS, total suppression of sidebands. 

Surface analytical techniques. A variety of spectroscopic methods have been used to characterize the nature of adsorbed species at the solid-water interface in natural and experimental systems (Brown et al, 1999). Surface spectroscopy techniques such as extended X-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) have been used to characterize complexes of fission products, thorium, uranium, plutonium, and uranium sorbed onto silicates, goethite, clays, and microbes (Chisholm-Brause et al, 1992, 1994 Dent et al, 1992 Combes et al, 1992 Bargar et al, 2000 Brown and Sturchio, 2002). A recent overview of the theory and applications of synchrotron radiation to the analysis of the surfaces of soils, amorphous materials, rocks, and organic matter in low-temperature geochemistry and environmental science can be found in Fenter et al (2002). 

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