Dynamical x-ray diffraction from a perfect crystal under grazing incidence conditions

Abstract

Synchrotron radiation obtained from the 6-T vertical-wiggler source at the Photon Factory has been used to study dynamical x-ray diffraction in a nearly perfect germanium crystal under total external reflection conditions. A specially designed goniometer has allowed independent control of the glancing angle and the deviation angle from exact Bragg incidence. The rocking-curve profiles observed from slightly asymmetric Bragg planes as a function of glancing angle were found to be quite different for both the diffracted and specular beams. These profiles show unusual features arising from the excitation or de-excitation of the wave fields in shallow surface layers of the bulk crystal. Furthermore, GeK fluorescence signals measured during the Bragg reflection showed characteristic modulations, demonstrating the feasibility of new standing-wave experiments for determination of interface structures.