Eur. Phys. J. Special Topics 208, 39-52 (2012)
https://doi.org/10.1140/epjst/e2012-01605-4

Review

Anisotropic resonant X-ray scattering: Beauty of forbidden reflections

¹ Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
² A.V. Shubnikov Institute of Crystallography, 119333 Moscow, Russia

^a e-mail: kokubun@ph.noda.tus.ac.jp

Received: 29 December 2011
Revised: 23 March 2012
Published online: 15 June 2012

Abstract

Experimental results and their theoretical explanation are reviewed for fundamentals of anisotropic resonant X-ray scattering. Resonant scattering depends on X-ray polarization, i.e. the scattering reflects anisotropic environment of atoms in crystal. The polarization anisotropy in atomic scattering can excite the forbidden Bragg reflections. Studying this type of forbidden reflections we can distinguish electronic orbitals of specific symmetry. This method is very useful for studying local electronic states in crystal. We reveal detailed property of the anisotropic scattering, effect of quadrupole transition, thermal motion, magnetic scattering and so on. Especially successful examples are given in detail: observation of phase of the scattering factor, the hybridization of states with different parity, local chirality of atom in centrosymmetric crystals, thermal-motion-induced resonant reflections, etc.