Coherent scattering of X-rays in a highly bent crystal

The analytical expressions for amplitudes of diffracted and transmitted,oaves have been obtained for X-ray symmetrical Laue-diffraction in the case of strongly-bent crystal. The effective decrease of crystal thickness, which is due to the reduce of X-ray coherent scattering region, have been established with the help of these expressions. This phenomenon arises because the processes of single and multiple scattering of incident wave are stopped when the bend of crystal is large enough. For the case of strongly-bent crystal, it has been shown that kinematical diffraction regime fakes place in coherent scattering region, if R << alpha xi(g)(2)g where R is the radius of crystal curvature, xi(g) is the extinction length, g is the reciprocal lattice vector, a is a constant describing the elastically-deformation properties of the crystal. While refraction of transmitted and diffracted waves, which are formed in the coherent scattering region, happens beyond this region. The estimates for sites of coherent scattering region, which are decreased with a subsequent increasing deformation, have been obtained both X-ray kinematical diffraction and X-ray dynamical one.