Research objectives and content
The content of this proposal is the theoretical and experimental expansion of the contrast generation of dislocation images in the three-beam case of X-ray diffraction. For that coplanar and non-coplanar three-beam cases in Laue-Laue, Bragg-Laue and Bragg-Bragg geometry are to be analyzed. The reflections will be selected in such a way that the topographical contrast conditions of the Umweg-wave are different from those of the direct wave. Cases, where the dislocation contrast in one of the involved reflections vanishes, are of special interest. The topographs by a psi-rotation of the crystal though the three-beam interference should be compared with the topographs by tuning the wavelength though this interference in a fixed arrangement. The proposed scientific program requires the brilliance, collimation, intensity, polarization, and wavelength tunability of the synchrotron radiation. The expectation of this work is to improve the resolution of the topograph and to get information about the mechanism of the interbranch scattering in the region of a dislocation .
Training content (objective, benefit and expected impact)
The work at the synchrotron radiation laboratory gives the possibility to get practical experience in the optical components of a beamline and to become familar with the several techniques for topography only available with synchrotron radiation (e.g. white beam topography; section topography with white beam, coherence effects).