Anomalous Transmission in Bragg-Case Diffraction of X-Rays

Abstract

Anomalous enhancement of a transmitted X-ray beam in Bragg-case diffraction is studied experimentally for the case that the direction of the diffracted beam comes close to the entrance surface of a target crystal. The intensity of the transmitted ray at µ 0 t =10 amounts to 30% of the incident beam, which is extremely stronger in comparison with observations up to the present. In this experiment (220)CrK α1 diffraction from a silicon single crystal is used in the double crystal spectrometer arrangement. Theoretical explanation for the phenomenon is also tried with a method which is more rigorous than the conventional two-waves approximation. A fairly good agreement is obtained between the experimental and theoretical results both for the anomalously transmitted intensity, and for the difference of the incident angle at which the intensities of the anomalously transmitted and diffracted beams reach to a maximum respectively.