Browsing by Author "Barnea, Z"

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    The Australian diffractometer at the Photon Factory
    (American Institute of Physics, 1992-01) Barnea, Z; Creagh, GC; Davis, TJ; Garrett, RF; Janky, S; Stevenson, AW; Wilkins, SW
    Outlined are design features of a versatile high‐resolution two‐axis diffractometer that is being constructed for operation at the Photon Factory as an Australian national facility. The instrument features optional use of multiple‐imaging plates on a translating cassette to allow rapid recording of an almost complete range of data covering both the high‐angle and small‐angle scattering regime or alternatively the use of electronic detectors. The instrument will be capable of operation in various modes including the following: (i) high‐resolution powder diffraction with single‐channel counter and crystal analyzer, (ii) high‐resolution, high‐speed powder diffraction in the Debye–Scherrer mode with imaging plates as recording medium, either stationary or translating (for time‐dependent studies), (iii) small‐angle x‐ray scattering with imaging plates as recording medium, (iv) protein crystallography in screenless Weissenberg mode, and (v) two‐ or three‐axis single‐crystal diffractometry. The salient features of the instrument are the use of a double‐crystal sagittal focusing monochromator as primary monochromator together with the optional use of a condensing–collimating channel‐cut (CCCC) monochromator or other channel‐cut monochromator as secondary monochromator. The use of a CCCC monochromator enables fine tuning of beam position on sample, harmonic suppression, beam‐condensation, and variation of wavelength bandpass. Further features include the use of high‐precision incremental encoders on both axes, together with the capability of operating the whole diffractometer, including secondary monochromator and detectors, in vacuum of order 10−3 Torr in order to reduce absorption and parasitic scattering, and the use of a large camera radius (approximately 0.57 m) for the imaging plate cassette in order to increase angular resolution and signal to noise. © 1992 American Institute of Physics.
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    Complex atomic fine structure in the phase domain: exciting opportunities and challenges
    (International Union of Crystallography, 2021-08-14) Tran, CQ; Chantler, CT; Kirk, T; Dao, MH; Di Pasquale, P; Ceddia, J; Barnea, Z; de Jonge, MD; Kewish, CM
    X-ray Absorption Spectroscopy has been one of the most powerful tools for probing atomic and molecular structures of materials. However, the measured fine structures in the absorption domain do not have adequate dimensionalities to extract three-dimensional structural information of the material of interest. A technique that allows accurate measurements of atomic fine structure in both the absorption and phase domains will open exciting opportunities in a wide range of fundamental and applied research. In this presentation, we will describe a new technique for determining simultaneously the real and imaginary components of the complex atomic form factor. The technique used Fourier Transform Holography with an extended reference and applicable to both crystalline and amorphous samples. Details of an application of the technique in spectroscopy mode to obtain the X-ray Complex Fine Structure across the copper K-edge will be discussed. © The Authors
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    Simultaneous reconstruction and structural fitting of the complex atomic fine structure of copper and iron
    (Australian Institute of Physics, 2022-12-11) Di Pasquale, P; Tran, CQ; Chantler, CT; Barnea, Z; Kirk, T; Dao, MN; Balaur, E; van Riessen, GA; Hinsley, GN; Jallandhra, A; Ceddia, J; Rogers, J; Kewish, CM; Paterson, DJ; Reinhardt, J; Kirby, N; Mudie, ST
    A novel technique for determining complex atomic fine structure will be described. Exciting applications of the technique such as a phase analogue to x-ray absorption fine structure applications will also be discussed.
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    X-ray mass attenuation coefficients and imaginary components of the atomic form factor of zinc over the energy range of 7.2-15.2 keV
    (American Physical Society, 2010-02) Rae, NA; Chantler, CT; Barnea, Z; de Jonge, MD; Tran, CQ; Hester, JR
    The x-ray mass attenuation coefficients of zinc are measured in a high-accuracy experiment between 7.2 and 15.2 keV with an absolute accuracy of 0.044% and 0.197%. This is the most accurate determination of any attenuation coefficient on a bending-magnet beamline and reduces the absolute uncertainty by a factor of 3 compared to earlier work by advances in integrated column density determination and the full-foil mapping technique described herein. We define a relative accuracy of 0.006%, which is not the same as either the precision or the absolute accuracy. Relative accuracy is the appropriate parameter for standard implementation of analysis of near-edge spectra. Values of the imaginary components f″ of the x-ray form factor of zinc are derived. Observed differences between the measured mass attenuation coefficients and various theoretical calculations reach a maximum of about 5% at the absorption edge and up to 2% further than 1 keV away from the edge. The measurements invite improvements in the theoretical calculations of mass attenuation coefficients of zinc. © 2010, American Physical Society