The structure of GexAs10Se90-x (x=10, 17.5, 22.5, 27.5, 30, 35) glasses as well as some other compositions extensively used in infrared optics, e.g. GASIR® (Ge22As20Se58) and AMTIR-1 (Ge33As12Se55) has been investigated by X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) measurements at the Ge, As and Se K-edges. Structural models have been obtained by fitting simult...

Ziegler-Natta polymerization catalysts were characterized by a complex of surface- and bulk-sensitive methods (DRIFTS, XPS, ESR, and XAS = XANES + EXAFS). A diffuse-reflectance Fourier-transform IR spectroscopy (DRIFTS) study showed the presence of strong Lewis acid sites in different concentrations and absence of strong basic sites in the polymerization catalysts. X-ray photoelectron spectrosc...

Understanding the chemical state of lead in fly ash generated from a waste thermal treatment is important, since the toxicity and solubility of the element depends on its chemical state. This study identified three potential methods for obtaining quantitative information regarding the chemical state of lead in fly ash: X-ray absorption near edge structure (XANES) analysis, extended X-ray absorp...

EXAFS spectroscopy has been used to compare the sorption mechanism of Zn and ZnEDTA on goethite (a-FeOOH). In the absence of EDTA, Zn is found to form an inner-sphere surface complex. Based on Zn-0 and Zn-Fe distances, Zn is inferred to be located in a distorted oxygen octahedron which shares edges andlor comers with surface Fe octahedra. EXAFS spectra of ZnEDTA in solution and sorbed on goethi...

Fig. 1. Mn XANES and EXAFS of single crystals of photosystem II as a function of x-ray dose. As the x-ray dose increases, Mn in PS II normally present as Mn4(III2,IV2) is reduced to Mn(II) as seen by the changes in XANES spectra (left bottom). The changes in the corresponding EXAFS spectra (right) show that the three Fourier peaks characteristic of Mn-bridging-oxo, Mn-terminal, and Mn-Mn/Ca int...

Diffraction anomalous fine-structure (DAFS) and extended x-ray absorption fine-structure (EXAFS) measurements were combined to determine short range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases of germanium. EXAFS yields information about the SRO of all Ge atoms in the sample, while DAFS determines the SRO of only the ordered fraction. We dete...

X-ray absorption near-edge structure (XANES) and extended fine-structure (EXAFS) spectra were recorded to investigate the electronic local crystal of ZnO ZnO:B powders produced via hydrothermal synthesis. grow as micrometre-scale rods with hexagonal shape, confirmed by scanning electron microscopy micrographs. The number broken increases increasing B concentration, observed in images, due atoms...

This work presents a study of the structural properties on four representative kaolinite samples. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Thermochemical Analyses (DTA/TGA), and Near Edge Structure (XANES) Extended Absorption Fine (EXAFS) spectroscopy measurements were carried out, different empirical indices that quantify order assessed. Also, XRD patterns EXAFS signals com...

The use of glancing angles to obtain EXAFS s igna ls from th in i n t e r f a c i a l regions is described. The technique is appl icable to the case of a l i g h t overlayer on a heavy subs t ra te f o r which t o t a l ex te rna l r e f l e c t i o n can be caused to occur a t the in te r face. I n t h i s case the penetrat ion i n t o the s u b s t r a t e i s very small (520-30 A i n many ca...