X-ray dichroism in noncentrosymmetric crystals

In this paper the authors analyze near-edge absorption of x rays in noncentrosymmetric crystals. The work is motivated by recent observations of x-ray dichroic effects which stem from parity-nonconserving electron interactions. We provide a theoretical description of these experiments and show that they are sensitive to microscopic polar and magnetoelectric properties of the sample. Our derivation extends previous theoretical work on centrosymmetric systems and identifies interesting directions in the microscopic analysis of crystalline materials using x-ray-absorption spectroscopy. © 2003 The American Physical Society.