X-Ray Natural Circular Dichroism

Abstract

We report the first observation of natural circular dichroism (CD) in the x-ray region. Measurements at the Nd ${L}_{3}$ edge in single crystals of ${\mathrm{Na}}_{3}\mathrm{Nd}(\mathrm{digly}{)}_{3}\ifmmode \dot{}\else \.{}\fi{}2{\mathrm{NaBF}}_{4}\ifmmode \dot{}\else \.{}\fi{}6{\mathrm{H}}_{2}\mathrm{O}$ show CD with a dissymmetry factor $g\ensuremath{\approx}{10}^{\ensuremath{-}3}$ of the same order of magnitude as observed in the visible-uv region and $\ensuremath{\sim}100$ times greater than in the vibrational infrared. Calculations using multiple scattering theory (MST) are in excellent agreement with the measured CD in the near-edge region (about 100 eV from the rising edge) and show that the effect arises from the electric dipole-electric quadrupole interference mechanism.