X-Ray Diffractometry

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Masaharu Takehara - One of the best experts on this subject based on the ideXlab platform.

Toshiki Kingetsu - One of the best experts on this subject based on the ideXlab platform.

E Koppensteiner - One of the best experts on this subject based on the ideXlab platform.

  • Triple crystal x‐ray Diffractometry of periodic arrays of semiconductor quantum wires
    Applied Physics Letters, 1993
    Co-Authors: Václav Holý, E Koppensteiner, Leander Tapfer, G. Bauer, H. Lage, Oliver Brandt, Klaus H. Ploog

    Kinematical diffraction theory and the optical coherence formalism have been used for calculating the diffuse x‐ray scattering from periodic quantum wires. The method calculates the distribution of the diffusely scattered intensity in the reciprocal lattice plane. The simulated distributions have been compared with those measured on a InAs/GaAs quantum wire by means of triple crystal x‐ray Diffractometry and a good agreement has been achieved. The method can be applied to studies of internal stress relaxation in quantum wires.

  • X-Ray Diffractometry of small defects in layered systems
    Journal of Physics D: Applied Physics, 1993
    Co-Authors: V. Holy, J Kubena, E. Abramof, A. Pesek, E Koppensteiner

    X-Ray diffraction in thin layers and layered systems is described using the optical coherence approach and the semi-kinematical diffraction theory. Two defect models in thin layers are considered-the mosaic structure model and the model of interface roughness. For both defect models the reflection curves of a thin layer and a superlattice have been calculated and compared with double-crystal X-Ray Diffractometry results on superlattices and epitaxial layers. The distribution of the diffusely scattered intensity near a reciprocal lattice point has been calculated theoretically for both models and it has been proved experimentally by double- and triple-crystal Diffractometry of epitaxial layers with mosaic structure. It has been demonstrated that the theory yields a tool for estimating the predominant defect type in a layered structure.

Dimas A. M. Zaia - One of the best experts on this subject based on the ideXlab platform.

  • Adsorption of Adenine and Thymine on Zeolites: FT-IR and EPR Spectroscopy and X-Ray Diffractometry and SEM Studies
    Origins of Life and Evolution of Biospheres, 2012
    Co-Authors: Cristine E. A. Carneiro, Ivan G. Souza Junior, Cláudio M. D. Souza, Antonio C. S. Costa, Eduardo Mauro, Cássia T. B. V. Zaia, Joaquin Coronas, Clara Casado, Henrique Santana, Dimas A. M. Zaia

    The interactions of adenine and thymine with and adsorption on zeolites were studied using different techniques. There were two main findings. First, as shown by X-Ray Diffractometry, thymine increased the decomposition of the zeolites (Y, ZSM-5) while adenine prevented it. Second, zeolite Y adsorbed almost the same amount of adenine and thymine, thus both nucleic acid bases could be protected from hydrolysis and UV radiation and could be available for molecular evolution. The X-Ray Diffractometry and SEM showed that artificial seawater almost dissolved zeolite A. The adsorption of adenine on ZSM-5 zeolite was higher than that of thymine (Student-Newman-Keuls test-SNK p  

  • Adsorption of cysteine on hematite, magnetite and ferrihydrite: FT-IR, Mössbauer, EPR spectroscopy and X-Ray Diffractometry studies
    Amino acids, 2010
    Co-Authors: Alessandra Paula Vieira, Ivan G. Souza Junior, Eduardo Mauro, Cássia T. B. V. Zaia, Henrique Santana, Graciele Berndt, Andrea Paesano, Antonio Carlos Saraiva Da Costa, Dimas A. M. Zaia

    In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mossbauer spectroscopy and X-Ray Diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constituents. There were two main findings described in this paper. First, after the cysteine adsorption, the FT-IR spectroscopy and X-Ray Diffractometry data showed the formation of cystine. Second, the Mossbauer spectroscopy did not show any increase in the amount of Fe2+ as expected due the oxidation of cysteine to cystine. An explanation could be that Fe2+ was oxidized by the oxygen present in the seawater or there occurred a reduction of cystine by Fe2+ generating cysteine and Fe3+. The specific surface area and pH at point of zero charge of the iron oxides were influenced by adsorption of cysteine. When compared to other iron oxides, ferrihydrite adsorbed significantly (p < 0.05) more cysteine. The pH has a significant (p < 0.05) effect only on cysteine adsorption on hematite. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the iron oxides even after being mixed with KCl and the amine and carboxylic groups are involved in this interaction. X-Ray Diffractometry showed no changes on iron oxides mineralogy and the following precipitated substances were found along with the iron oxides after drying the samples: cysteine, cystine and seawater salts. The EPR spectroscopy showed that cysteine interacts with iron oxides, changing the relative amounts of iron oxides and hydroxide.

Kenjiro Ito - One of the best experts on this subject based on the ideXlab platform.