The sorption capacity of montmorillonite clay minerals for small cations, such as Ni , can be greatly enhanced by modifying the clay mineral with Al(III). In this study, the mechanisms of Ni uptake by Al-modified montmorillonite were studied using extended x-ray absorption fine structure (EXAFS) spectroscopy of powders and polarized EXAFS spectroscopy of self-supporting clay films to delineate ...

X-ray absorption spectroscopic studies of cation environments in oxide glasses are selectively reviewed. New results are presented on K and Yb environments in silicate glasses and on Fe in silicate melts at temperatures up to 1173 " K. INTRODUCTION Recent investigations of oxide glasses and crystalline model compounds by x-ray absorption spectroscopy (XAS and the acronyms EXAFS for extended fin...

Direct industrial application of x-ray absorption spectroscopy is demonstrated by research in catalysis (CO/H2 and naphtha reforming) and corrosion protection.

Toward Quantitative Calculation and Analysis of X-Ray Absorption Near Edge Spectra Joshua Kas Chair of the Supervisory Committee: Professor John Rehr Physics X-ray absorption spectroscopy (XAS) has been used extensively to determine local electronic and structural properties. While quantitative analysis of extended x-ray absorption fine structure (EXAFS) has been available for over two decades,...

Chlorine (Cl) is a constituent of certain types of nuclear wastes and its presence can affect the physical and chemical properties of silicate melts and glasses developed for the immobilization of such wastes. Cl K-edge X-ray absorption spectra (XAS) were collected and analyzed to characterize the unknown Cl environments in borosilicate waste glass formulations, ranging in Cl-content from 0.23 ...

Gamma radiation induced changes in local structure around the probe atom (Hafnium) were investigated in sodium barium borosilicate (NBS) glass, used for immobilization of high level liquid waste generated from the reprocessing plant at Trombay, Mumbai. The (NBS) glass was doped with 181Hf as a probe for time differential perturbed angular correlation (TDPAC) spectroscopy studies, while for stud...

Metal ions in metallo-β-lactamases (MBLs) play a major role in catalysis. In this study we investigated the role of the metal ions in the Zn1 and Zn2 sites of MBL L1 during catalysis. A ZnCo (with Zn(II) in the invariant Zn1 site and Co(II) in the Zn2 site) analog of MBL L1 was prepared by using a biological incorporation method. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopic st...

Grignard Compounds RMgX (R=organic group; X=Cl, Br, I) are common tools in inorganic and organic synthesis. The structure of these substances in solution, however, is unknown. To answer this question we performed EXAFS measurements at the Br-K-edge in absorption mode and at the Mg-K-edge in fluorescence mode. Rom these complementary data a consistent model of the structure of the investigated G...

Copper and zinc were introduced into mesoporous siliceous matrices with the goal of obtaining model methanol synthesis catalysts with intense interaction between copper and the ZnO promoter. The preparation methods included various aqueous routes starting from acetate solutions (into MCM-48) and a route involving an organometallic step—thermolysis of a liquid heterocubane of Zn4O4 type ([CH3ZnO...