Dynamical effects in the integrated X‐ray scattering intensity from imperfect crystals in Bragg diffraction geometry. I. Semi‐dynamical model

• Published in: Acta crystallographica. Section A, Foundations and advances Vol. 76; no. 1; pp. 45 - 54
• Main Authors: Molodkin, V. B., Olikhovskii, S. I., Dmitriev, S. V., Nizkova, A. I., Lizunov, V. V.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.01.2020
• Subjects: Borrmann effect; Bragg diffraction geometry; Coulomb‐type defects; diffuse scattering; dynamical X‐ray diffraction theory; extinction; extinction; Borrmann effect; diffuse scattering; dynamical X-ray diffraction theory; Coulomb-type defects; Bragg diffraction geometry
• ISSN: 2053-2733; 2053-2733
• DOI: 10.1107/S2053273319014281

The analytical expressions for the coherent and diffuse components of the integrated reflection coefficient are considered in the case of asymmetric Bragg diffraction geometry for a single crystal of arbitrary thickness, which contains randomly distributed Coulomb‐type defects. The possibility to choose the combinations of diffraction conditions optimal for characterizing defects of several types by accounting for dynamical effects in the integrated coherent and diffuse scattering intensities, i.e. primary extinction and anomalous absorption, has been analysed based on the statistical dynamical theory of X‐ray diffraction by imperfect crystals. The measured integrated reflectivity dependencies of the imperfect silicon crystal on azimuthal angle were fitted to determine the diffraction parameters characterizing defects in the sample using the proposed formulas in semi‐dynamical and semi‐kinematical approaches. The sensitivity of the integrated X‐ray diffraction intensity to different Coulomb‐type defects in real crystals is the subject of theoretical research in the case of Bragg diffraction geometry. The diffraction parameters characterizing defects in the test sample of silicon are determined using the proposed approximate formulas.