The Ratio of the Modified to the Total Scattering Coefficient of X-Rays

Abstract

Use has been made of the fact that the modified portion of scattered x-rays has not only a greater wave-length but also a greater absorption coefficient than the primary x-rays in order to separate the modified and unmodified portions of a scattered x-ray beam. The method involves the change in the intensity of scattered x-rays when a given thickness of aluminum is transferred from the primary to the scattered beam. Using a balance method, measurements of the ratio of the modified to the total scattering coefficient have been made for x-rays of wave-lengths 0.27A to 0.58A scattered from carbon, aluminum and copper at angles varying from 60° to 130°. Comparison with theory. Jauncey's theory predicts that the ratio should become unity when vers $\phi =\frac{242{{\lambda }_0}^2}{{\lambda }_s}$ (${\lambda }_s$ and ${\lambda }_0$ being measured in Angstroms). For carbon at 60° and 90° the experimental ratio becomes unity at wave-lengths of 0.32A and 0.46A respectively: The theory gives 0.31A and 0.44A respectively. A calculation of the modified scattering coefficient for copper at 90° for $\lambda =0.4\mathrm{}\mathrm{A}$ gives $0.71s_0$ (where $s_0$ is the Thomson coefficient at 90°), while the theory gives $0.74s_0$. Thus as far as they go the experiments are in agreement with the theory.