Temperature-dependent local structure and lattice dynamics of yttria (Y2O3) were studied by X-ray absorption spectroscopy. Novel method, which combines the reverse Monte Carlo and evolutionary algorithm techniques, was applied for the analysis of extended X-ray absorption fine structure at the Y K-edge. This approach allowed us to reconstruct 3D atomic structure models of crystalline and nanocr...

Thin films of copper indium diselenide (CIS) were prepared by chemical bath deposition technique onto glass substrate at 60C. The studies on composition, morphology, optical absorption, electrical conductivity and structure of the films were carried out. Characterization includes X-ray diffraction (XRD), Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Energy dispersive x-ray ...

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,...

We present the results of an analysis of data from XMM-Newton and CHANDRA observations of the high luminosity narrow-line quasar PG 1404+226. We confirm a strong soft X-ray excess in the X-ray spectrum and we find rapid variability (a factor of two in about 5000 s) in both XMMNewton and CHANDRA data. When the X-ray spectrum is fit with a two component model which includes a power-law (Γ ∼ 1.6) ...

Variable X-ray Absorption in High-Mass X-ray Binaries Cygnus X-1 and Vela X-1

We use numerical simulations of structure formation in a Cold Dark Matter model to predict the absorption lines in the soft X-rays produced by heavy elements in the shock-heated intergalactic medium at low redshift. The simulation incorporates a model for heavy element production in galaxies and the subsequent dispersion of the metals to the intergalactic medium. We analyze in particular absorp...

We report the discovery of X-ray broad absorption lines (BALs) from the BALQSO APM 08279+5255 originating from material moving at relativistic velocities with respect to the central source. The large flux magnification by a factor of ∼ 100 provided by the gravitational lens effect combined with the large redshift (z = 3.91) of the quasar have facilitated the acquisition of the first high signal...

A high-order multiple-scattering (MS) approach to the calculation of polarized x-ray-absorption spectra, which includes both x-ray-absorption ne structure (XAFS) and x-ray-absorption near-edge structure (XANES), is presented. EEcient calculations in arbitrary systems are carried out by using a curved-wave MS path formalism that ignores negligible paths, and has an energy-dependent self-energy a...

Selenium compounds exhibit chemopreventative properties at supranutritional doses, but the efficacy of selenium supplementation in cancer prevention is dependent on the chemical speciation of the selenium supplement and its metabolites. The uptake, speciation, and distribution of the common selenoamino acid supplements, selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys), in A549 hum...