Forbidden reflections excited owing to the anisotropy of X-ray susceptibility. I. Interference with the Renninger reflections

Interference between multiple-beam Renninger reflections and "forbidden" reflections, which are excited owing to the anisotropy of X-ray susceptibility of atoms, is considered. It is shown that the tensor structure factors of "forbidden" reflections due to the glide-plane and (or) screw-axis can be completely determined from X-ray data. Both real and imaginary parts of the local polarization anisotropy of atoms can be measured using this method, even in cubic crystals. A detailed calculation is presented for a FeS2 (pyrite) crystal.