X-ray birefringence and forbidden reflections in sodium bromate

Abstract

Reflections forbidden by a screw-axis rule are observed in sodium bromate with synchrotron radiation near the bromine K absorption edge, where X-ray birefringence occurs. The intensities vary with azimuthal angle according to theoretical predictions and indicate a larger magnitude for the birefringence than did earlier experiments. This technique is a method of selective diffraction in which atoms of a single element in a single chemical state contribute to the signal, and it can reveal their positions with precision.