Anomalous Enhancement of Transmitted Intensity in Asymmetric Diffraction of X-Rays from a Single Crystal

A theoretical and experimental study has been made on the anomalous transmission of X-rays in the Laue-case diffraction of nearly perfect crystals with a special reference to the asymmetric diffraction. For the theoretical analysis the dispersion equation has been solved to an approximation higher than that usually used, because the usual two-wave approximation is rather poor in the extremely asymmetric case of diffraction. The theoretical analysis shows that the intensity of the anomalously transmitted wave increases with the asymmetry of diffraction and reaches 42% of the incident intensity when \(μ{·} t{}10\). These facts have been confirmed experimentally with the use of the parallel setting of the double-crystal arrangement, in which (220) diffraction of Si is used with CrK α1 .