DIRECTION OF THE ENERGY FLOW IN PERFECT CRYSTALS-NEAR THE ATOMIC ABSORPTION EDGE

Abstract The direction of the energy flow in perfect crystals near the atomic absorption edge is studied in detail in the symmetrical Laue and Bragg cases. It is found that in the symmetrical Laue case, the direction of the energy flow corresponding to a tie point on the dispersion surface deviates from the normal of the real part of the dispersion surface, only when the contribution of the imaginary part of the atomic scattering factor to the diffraction is comparable to that of the real part. However, in the symmetrical Bragg case, the deviation takes place in the so called “total reflection” region even when the contribution of the imaginary part of the atomic scattering factor to the diffraction is negligible. When diffraction is induced only by the imaginary part of the atomic scattering factor, the deviation becomes the largest in the Laue case, but the least in the Bragg case.