X-ray natural circular dichroism of gyrotropic crystals.

X-ray natural circular dichroism of gyrotropic crystals crystals due to the substantial contribution in the X-ray range of the Electric Dipole-Electric Quadrupole (El.E2) interference terms first investigated by Barron at optical wavelengths (Barron, 1971). We will discuss first which crystal class is appropriate to detect XNCD and we will give a general formulation of the XNCD cross sections o (El .E2).