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Effects of surface undulations on asymmetric X‐ray diffraction: a rocking‐curve topography study
Author(s) -
Macrander Albert,
Pereira Nino,
Huang Xianrong,
Kasman Elina,
Qian Jun,
Wojcik Michael,
Assoufid Lahsen
Publication year - 2020
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/s1600576720005166
Subject(s) - diffraction , reflection (computer programming) , surface (topology) , x ray , optics , asymmetry , crystal (programming language) , x ray crystallography , angle of incidence (optics) , materials science , physics , crystallography , geometry , chemistry , mathematics , quantum mechanics , computer science , programming language
The results are reported of an X-ray diffraction study of an Si crystal designed and fabricated for very asymmetric diffraction from the 333 reflection for X-ray energies of 8.100 and 8.200 keV. A crystal with an asymmetry angle of 46 ± 0.1° between the surface and the (111) planes was studied. The grazing angles of incidence were near 1.08 and 0.33° for these two energies, respectively. Features arising from surface undulations were not observed at 8.100 keV, but were observed at 8.200 keV. The results at 8.100 keV allow an alternative explanation based on strain near the surface to be ruled out. Topographic images were obtained as a function of rocking angle, and in the case of 8.200 keV the surface morphology is evident. The results are found to be in agreement with dynamical X-ray diffraction calculations made with the Takagi–Taupin equations specialized to a surface having convex or concave features, as reported in the accompanying paper [Macrander (2020). J. Appl. Cryst. 53 , 793–799].