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The Resolution Function of a Triple‐Crystal Diffractometer for High‐Energy Synchrotron Radiation. II. Dispersive Laue Geometry
Author(s) -
Rütt U.,
Neumann H.B.,
Poulsen H. F.,
Schneider J. R.
Publication year - 1995
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889895005516
Subject(s) - monochromator , diffractometer , optics , synchrotron radiation , bar (unit) , resolution (logic) , physics , scattering , diffraction , crystal (programming language) , bragg's law , streak , synchrotron , geometry , wavelength , scanning electron microscope , mathematics , artificial intelligence , meteorology , computer science , programming language
The k ‐space resolution function of a new triple‐crystal diffractometer for high‐energy synchrotron radiation is calculated for an arrangement of three perfect silicon crystals diffracting in dispersive Laue geometry. A comparison is made with the results of measurements using 100 keV synchrotron radiation. The settings (0, 111, 0) and (0, 400, 0) are discussed in detail. All features of the measured resolution function are well reproduced by the calculations, especially if the background due to non‐Bragg scattering from the collimators and the crystals is taken into account. In addition, approximate formulas are presented that provide a quick survey over the features of the resolution in k space for a given experimental set‐up. On the 50% contour level, the λ streak is by far the dominating feature of the resolution function and reduces the resolution parallel to G sample by a factor of 40 to about 8 × 10 −3 Å −1 . The excellent resolution in the scattering plane perpendicular to G sample of 10 −5 Å −1 is not affected. Unlike in the nondispersive case and diffraction experiments using characteristic lines of X‐ray tubes, here the location and the intensity distribution of the monochromator streak depend on the Bragg angles of the monochromator, sample and analyzer crystal.