Interbranch transient beating of X-ray intensities in deformed crystals.
X-ray dynamical diffraction in a deformed crystal is studied using the interbranch resonance concept. It is shown that appreciable beating of the X-ray intensities may be induced by a lattice distortion that produces interbranch transformations of the local dispersion surface. In X-ray plane-wave topography, this effect may be observed as interference fringes arising around the kinematical image of a defect. It is predicted that such interbranch fringes can be induced by edge dislocations.
X-ray interbranch resonance as a new idea to solve the diffraction problem for bent crystals
The resonance concept is extended for x-ray interbranch scattering by a bent crystal with a uniform strain gradient. Splitting each of the branches of the dispersion surface follows from these considerations. It is shown that interbranch crossover is due to interference of the waves corresponding to ‘new’ branches, making up the ‘new’ Bloch-modes.
Observation of Phase change of X-ray Polarizability by Rocking Curves in the Bragg Case
Rocking curves of the reflected and transmitted beams for GaAs 600 in the symmetric Bragg case were measured just below the K-absorption edge of Ga using X-rays from synchrotron radiation. Asymmetry and its reversal of the rocking curves for the transmitted beam were observed: the rocking-curve intensity in the lower-angle region of the exact Bragg angle was larger than that in the higher-angle region when the X-ray energy was 9 eV below the edge, while the asymmetry was reversed when the X-ray energy was about 6 eV below the edge. The reversal has been found to result from the change in the phase of X-ray polarizability.