Redetermination of the Temperature Dependence of X Rays Anomalously Transmitted through Germanium

Abstract

We have redetermined the temperature dependence of the anomalously transmitted x rays through single crystals of germanium of effective thicknesses, ${\mu }_{0}t=20\mathrm{} \mathrm{and} 30$. We have established, as suggested by Okkerse, that the earlier measurements were subject to error due to a thermal gradient perpendicular to the diffracting planes. By suitable rearrangement of the heating geometry this type of gradient was substantially removed. The current results are in agreement with those of Okkerse and indicate that the data can be explained by allowing the imaginary part of the scattering factor to depend on temperature as $\exp \mathrm{}(-M)\mathrm{}$ where $M$ is based on a Debye temperature of 291°K. It is felt that there is insufficient evidence at present to conclude in general that the temperature dependence in dynamical diffraction is $\exp \mathrm{}(-M)\mathrm{}$.