Wavelength Dependence of Moderate Extinction Effects in an Extended-Face Crystal of Cadmium Selenide

摘要

X-ray intensity measurements have been carried out with an extended-face single crystal of hexagonal CdSe using four different wavelengths. The wavelength dependence of moderate extinction effects (y > 0.7, where y is the secondary extinction factor) was investigated by analysing the Bragg intensities using Zachariasen's (1967) theory, with and without the sin2(theta) factor (theta being the Bragg angle) omitted from the original expression for the diffraction cross-section in a perfect crystallite. The resulting Hamilton's (1965) R-factors for the different extinction models tested do not enable one to make conclusive statements in regard to the best model, but the refined values of the domain radius r and the mosaic-spread parameter g suggest that the crystal is neither of type I (r >> (lambda)g) nor type II (r << (lambda)g). The wavelength dependence of the extinction effects is adequately accounted for in terms of the models tested. (Atomindex citation 16:047435)