Extension of resonant X-ray scattering by using K-K relationship in soft X-ray reflectivity

Resonant X-ray scattering is powerful technique for the study of electronic structure at the nanoscale. However, the optical properties of the constituent components of a material must be known prior to modeling of the scattered intensity. Professor J. B. Kortright (Lawrence Berkeley National Laboratory, USA) and his collaborator have recently proposed a method of refining electronic structure, in the form of optical properties, simultaneously with physical structure, in a Kramers-Kronig (K-K) consistent manner. This technique has been applied to specular reflectivity from a SrTiO₃ single crystal, and both a nonresonant surface contaminant layer and a modified SrTiO₃ surface region have been evidenced. For more information, see the paper, "Kramers-Kronig constrained modeling of soft x-ray reflectivity spectra: Obtaining depth resolution of electronic and chemical structure", K. H Stone et al., Phys. Rev. B86, 024102 (2012).