Anisotropic x-ray anomalous diffraction and forbidden reflections

Abstract

In this paper the authors present a general analysis of resonant elastic scattering of x rays. The approach exploits crystal symmetry, scattering geometry, and polarization. Extinction rules, their breaking, and the observation of forbidden reflections are discussed. As an application, a detailed description of the experiment performed by Finkelstein, Shen, and Shastri at the iron $K$ edge in $\ensuremath{\alpha}$ ${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$ (hematite) is reported.