Theoretical Considerations on Bragg-case Diffraction of X-rays at a Small Glancing Angle

X-ray diffraction phenomenon, for which the glancing angle of the incident beam is so small that the effect of specular reflection can not be neglected, is studied theoretically. Two wave fields, one of which is usually neglected, are considered as the solution of the dispersion equation, and the boundary conditions of the waves are considered for the gradient of amplitude normal to the surface besides the amplitude. Numerical calculations are made for (220) reflection of CuK α1 from a germanium single crystal. The diffracted beam is stronger in intensity and broader in half-value width than that where specular reflection is not considered.