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Some specific features of synchrotron X-ray absorption and scattering in matter are considered as a basis for the methods of studying the electronic, magnetic, phonon, and structural properties of condensed media. Their theoretical description is given within the quasirelativistic approximation of the Dirac equation. This makes it possible not only to describe the experimentally observed phenomena, but also to predict new spin-position effects in resonant scattering. [ABSTRACT FROM AUTHOR]

The sequential derivation of an expression that describes an X-ray natural circular dichroism (XNCD) signal in the most general case is performed. The obtained expression is used as a basis to consider XNCD signals and their structural origins in copper metaborate CuB2O4 crystals at an incident radiation energy near the K absorption edge of copper and lanthanum-gallium silicate La3Ga5SiO14 crystals at an incident radiation energy near the K absorption edge of gallium. It has been demonstrated that the measurements of circularly polarized X-ray absorption spectra in combination with corresponding first-principle calculations provide an efficient method for studying the contributions of crystallographically non-equivalent atoms to the X-ray optical activity of crystals. [ABSTRACT FROM AUTHOR]