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Potential use of V-channel Ge(220) monochromators in X-ray metrology and imaging

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      Abstract

      Several ways of tuning a higher asymmetry factor (>10) in V-channel X-ray monochromators, for metrological and imaging applications, were analysed. A more than sixfold intensity increase for compositionally and thermally tuned cases was achieved.

      Abstract

      While channel-cut crystals, in which the diffracting surfaces in an asymmetric cut are kept parallel, can provide beam collimation and spectral beam shaping, they can in addition provide beam compression or expansion if the cut is V-shaped. The compression/expansion ratio depends in this case on the total asymmetry factor. If the Ge(220) diffraction planes and a total asymmetry factor in excess of 10 are used, the rocking curves of two diffractors will have a sufficient overlap only if the second diffractor is tuned slightly with respect to the first one. This study compares and analyses several ways of overcoming this mismatch, which is due to refraction, when the Cu Kα 1 beam is compressed 21-fold in a V21 monochromator. A more than sixfold intensity increase was obtained if the matching was improved either by a compositional variation or by a thermal deformation. This provided an intensity gain compared with the use of a simple slit in a symmetrical channel-cut monochromator. The first attempt to overcome the mismatch by introducing different types of X-ray prisms for the required beam deflection is described as well. The performance of the V-shaped monochromators is demonstrated in two applications. A narrow collimated monochromatic beam obtained in the beam compressing mode was used for high-resolution grazing-incidence small-angle X-ray scattering measurements of a silicon sample with corrupted surface. In addition, a two-dimensional Bragg magnifier, based on two crossed V15 channel monochromators in beam expansion mode and tuned by means of unequal asymmetries, was successfully applied to high-resolution imaging of test structures in combination with a Medipix detector.

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      Affiliations
      [a ]Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovakia
      [b ]ANKA Light Source, Karlsruhe Institute of Technology, Karlsruhe, Germany
      [c ]Institute of Physics, SAS, Dúbravská cesta 9, 845 11 Bratislava, Slovakia
      [d ]Sincrotrone Trieste ScpA, Basovizza (TS), Italy
      [e ]Alexander Dubček University of Trenčín, Študentská 2, SK-911 50 Trenčín, Slovakia
      [f ]CNR IMEM Institute, Viale Usberti 37/A, Parma, 43124, Italy
      [g ]CEITEC, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
      [h ]FMF, Freiburg, Germany
      Author notes
      Correspondence e-mail: elekdkor@ 123456savba.sk
      [‡]

      Correspondence address: Department of Technology and Diagnostics of Semiconductors, IEE SAS, Vrbovská cesta 110, 921 01 Piešt’any, Slovakia.

      Journal
      J Appl Crystallogr
      J Appl Crystallogr
      J. Appl. Cryst.
      Journal of Applied Crystallography
      International Union of Crystallography
      0021-8898
      01 August 2013
      07 June 2013
      07 June 2013
      : 46
      : Pt 4 ( publisher-idID: j130400 )
      : 945-952
      24046503
      3769071
      xk5006
      10.1107/S0021889813006122
      JACGAR S0021889813006122
      © D. Korytár et al. 2013

      This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

      Categories
      X-Ray Diffraction and Imaging

      Analytical chemistry

      montel optics, bragg magnifier, channel-cut crystal, metrology

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