Self-aligned nanostructures (SAN) made by reacting Co nanoparticles with crystalline Si substrates at high temperatures were studied with grazing incidence X-ray absorption spectroscopy (GI-XAS). The results from extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge spectroscopy (XANES) were used to identify SAN as crystalline CoSi2. Theoretical calculations o...

We discuss the gamma-ray absorption in the inner region of the microquasar SS433. Our investigation includes several contributions to the opacity of this system. They result from the ambient fields generated by the primary star, possibly an A-type supergiant, and a very extended disk around the black hole. We find an important source for gamma-ray absorption in the UV photon field from the exte...

The Mg K-edge and Zn K- and L3-edge X-ray absorption near edge spectra of Mg and Zn porphyrins in the ground state and low-lying optically excited states are calculated. Also computed are X-ray absorption near edge spectra of Fe(II) spin crossover compound in its ground and low-lying optically excited states, motivated by a recent experiment (J. Phys. Chem. A 2006, 110, 38). The calculated abso...

An X-ray contact microscopy system has been developed for the study of molecular and elemental distributions in biological specimens based on X-ray absorption characteristics. The system consists of a chamber for measuring XANES (X-ray absorption near-edge structure) of biomolecules, and a contact microscopy system for dried specimens with an electronic zooming tube. With this system the elemen...

Calcium fluoride nanoparticles with special amount of cerium ion (%1) were synthesized by coprecipitation. Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), absorption and photoluminescence (PL) from CaF2Ce nanoparticles has been investigated. FTIR spectra reveal that there are some amounts of OH, NO3 and other organic functional groups on the parti...

X-ray fluorescence spectroscopy is a widely used method for determining the electronic configuration and local structure of dilute species with high sensitivity. In the dilute limit, and for thin films, the X-ray fluorescence signal is directly proportional to the atomic sub-shell absorption coefficient. However, for concentrated samples, the well-documented self-absorption effect often leads t...

The aim of this project is the calculation of the absorption coefficient μ of xray absorption spectra as a function of energy and a comparison with experimental data. A characteristic fine structure can be found in x-ray absorption spectra (XAS) consisting of the XANES (X-Ray Absorption Near Edge Structure) and the EXAFS (Extended X-Ray Absorption Fine Structure) region. XANES is characterized ...

Scattering and absorption of X-rays by interstellar dust is calculated for a model consisting of carbonaceous grains and amorphous silicate grains. The calculations employ realistic dielectric functions with structure near X-ray absorption edges, with resulting features in absorption, scattering, and extinction. Differential scattering cross sections are calculated for energies between 0.3 and ...

Non-destructive microscale investigation of objects is an invaluable tool in life and materials sciences. Currently, such investigation is mainly performed with x-ray laboratory systems, which are based on absorption-contrast imaging and cannot access the information carried by the phase of the x-ray waves. The phase signal is, nevertheless, of great value in x-ray imaging as it is complementar...