Multiparametric crystallography using the diversity of multiple scattering patterns for Bragg and diffuse waves. Method of standing diffuse waves

Abstract

The fundamentals of a new-generation crystallography developed by the authors, known as diffuse-dynamical multiparametric diffractometry (DDMD), are reviewed. Kovalchuk and Kohn, in their classic paper “X-ray standing waves—a new method of studying the structure of crystals“ (Sov. Phys. Usp. 29 426 (1986)) provided theoretical and experimental justification for applying the method of X-ray standing waves to perfect crystals. The present paper discusses the results of extending their work to crystals with defects in which standing diffuse waves arise in addition to X-ray standing waves. The effect exerted by defects on the dynamical scattering pattern then depends on the diffraction conditions, thus creating a new phenomenon that manifests itself in a widely diverse diffuse-dynamical picture inherently impossible for kinematical scattering. By adjusting the diffraction conditions, this allows modifying the Bragg and diffuse wave fields (from running to standing), and hence changing the character of the field interaction with the crystal, with the result that experiments can provide sufficiently many various scattering patterns for the problem of unique mulliparametric diagnosis to be solved by treating the patterns collectively. Theoretical and experimental fundamentals of DDMD and the results of its practical application are discussed.