In the usual treatment of the dynamical diffraction of x rays, one considers a plane wave which is incident on a crystal giving rise to a reflected plane wave. This work extends that theory by considering an incident bounded beam of x rays. We evaluate the resulting Bragg-reflected beam for both symmetric and asymmetric reflections and show that the reflected beam undergoes a lateral shift and that incidence at the edges of the range of total reflection results in a lateral wave traveling along the surface. This is analagous to the Goos-Hanchen effect for total internal reflection of an optical beam. In addition, if the incident beam is spectrally wide, the reflected beam is distorted and broadened, as well as shifted.

• Received 23 January 1989

DOI:https://doi.org/10.1103/PhysRevB.40.20