New Approaches and Possibilities of a Dynamical Diffractometry of Imperfections of Multiparameter Systems

Abstract

This review deals with discussions of findings of authors, the previously unknown phenomenon of amplification of manifestation of defects in statistical pattern of multiple scattering by several orders of magnitude as well as possibilities of using this phenomenon, taking into account its dispersive nature, which is also established by authors. As stressed, there is an additional new mechanism of influence of distortions on the wave vectors of scattered waves rather than on the amplitudes in case of multiple (dynamical) scattering (in contrast to the traditionally used kinematical theory, i.e. single-scattering approach). The revealed mechanism is exponentially more effective due to influences of defects on the power exponent directly (i.e. on the wave-function phase). The character of this influence is found to be controlled by the diffraction conditions (wavelength, object thickness, geometry and diffraction angles, etc.). For case of the most simple and express integral diffractometry, we discuss our previously established two conservation laws for the first and second parameters of kinematical theory of integral intensities. These are independence on characteristics of crystal distortions, namely, total (Bragg and diffuse) integral intensity of scattering, and independence on diffraction conditions, namely, diffuse component contribution to the total integral intensity. As demonstrated, these laws, being correct within the kinematical scattering, essentially restrict sensitivity and informativity of kinematical scattering pattern. At the same time, the revealed dispersion mechanism of the influence of defects on the multiple-scattering pattern results in the orientation-interference effects in the reflectivity and absorptivity of the crystals that causes violation of these laws in case of multiple scattering and hereby ensures unique indexes of sensitivity and informativity of diagnostics based on measurements of total integral intensity of dynamical diffraction and its diffusion component as well as their dependences on diffraction conditions. As a result, the discovered phenomenon and following effects as well as their dispersion nature allowed authors essentially extend diagnostics features and create state-of-the-art methods, which not only increased diagnostics sensitivity by several orders of magnitude, but also solved the problem of unambiguous diagnostics of multiparameter systems by means of combining measurements of multiple-scattering pattern in different diffraction cases.

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