3-BEAM DIFFRACTION IN FINITE IMPERFECT CRYSTALS - AN ANALYSIS OF COHERENT WAVE-FIELD INTERACTIONS USING STATISTICAL DYNAMICAL THEORY

By applying the concepts of statistical dynamical theory and the bound ary-value Green-function technique, an analytical expression in the fo rm of a series expansion has been obtained for the coherent contributi on to the integrated power in a finite crystal geometry. The solution suggests that three-beam interference is likely to cause observable pe rturbations also in crystals with a high degree of imperfection. Owing to a first-order dependence on the invariant triplet phase sum, profi le reversal may occur in cases where this sum is close to 90 degrees. The result may serve as an experimental check on statistical dynamical parameters.