Thermal Diffuse Scattering of X-Rays by Potassium Bromide Crystals

Abstract

The lattice dynamics of potassium bromide was studied by the measurement of intensities of X-ray thermal diffuse scattering. The observation was made on single crystals of KBr, with faces parallel to (001) and (011), kept in a vacuum chamber at 20°C. CuK_α X-rays monochromatized by a quartz crystal were focused on the surfaces of KBr. The intensities of scattered X-rays were measured by using a scintilation counter with a pulse height analyzer.
The effects of longitudinal lattice waves travelling in the directions [001] and [011] were investigated. The measured intensities agreed with the theoretical intensities calculated by using the simple shell model of ions, but not with those calculated by using the rigid ion model.