![]() ![]() Thus, we may conclude the following: concerning the divergence:ĭ > w h Qthey produce exclusively divergent waves beamline ID19 :ĭ w h l non-monochromatic (more often case)ĭl s > w h lwhite beam, always non-monochromatic Table 3: The normalised spectral width, Dl s, for the beam from a laboratory source, a "monochromatised" synchrotron beam, and a "white" synchrotron beam. References and further details may be found e.g. The basic principle of X-ray topography is shown in Fig.1. In this way topography is a study of the fine structure of a Bragg spot which contains the information about the departures from the perfect crystal structure (which is investigated by structure determination methods and assumed as known), that is the defect structure. This becomes possible, because these distortion fields may affect the diffracted intensity, so give "contrast" (non-homogeneous intensity distribution) in the image. More exactly, it records the long range distortion fields and/or the strain fields associated with a macroscopic crystal deformation (e.g. It is used for the visualisation of defects (dislocations, twins, domain walls, inclusions, impurity distribution, …) present in the crystal volume. It provides a two dimensional intensity mapping of the beam(s) diffracted by a crystal. X-ray diffraction topography is an imaging technique based on Bragg diffraction (Bragg’s law l = 2 dhkl sinQ B, with l - X-ray wavelength, dhkl - lattice plane spacing, QB - Bragg angle). ![]() Basic diffraction topographic techniquesĢ.2 Section topography (limited beam method)ĥ. An Overview of Techniques and ApplicationsĢ. ![]()
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