Heights and widths of Umweganregung profiles in comparison with Bragg reflection profiles
Abstract
The excellent agreement between experimental Umweganregung patterns and those calculated with UMWEG90 Rossmanith (1992). Acta Cryst. A48, 596-610 has been demonstrated by Rossmanith, Adiwidjaja, Eck, Kumpat & Ulrich J. Appl. Cryst. (1994), 27, 510-516. It has also been shown that, by fitting calculated to experimental scans, consistent and physically significant parameters for the mosaic structure parameters of the sample - mosaic spread and mosaic block size - and for the divergence parameter of the X-ray beam can be obtained. In this paper, it is shown that, furthermore, the relative intensities of scans of different forbidden reflections of a particular sample are predicted satisfactorily with UMWEG90 using the parameters obtained in the previously mentioned paper. To make an appraisal of the possible maximum gain due to Umweganregung, -2- scans of 14 forbidden reflections of a particular zinc sample were analysed. By comparison of the -2 intensity profiles and integrated intensities of the multiple diffraction events with those of the rocking curves of 15 Bragg reflections with neighbouring Bragg angles, the statements given in standard textbooks, that the profiles of Umweganregung events are much sharper and the intensities much smaller than those of possible Bragg reflections, are disproved.