THE IMPACT OF THE REFLECTION ASYMMETRY OF THE PRIMARY X-RAY BEAM AND THE ROLE OF DIVERGENCE ON THE STRUCTURE OF THE TOPOGRAM REFLEX
The structure of reflexes has been investigated in the case when there are surface deformed layers in the crystal, depending on the character of absorption and dispersion of X-rays by the deformed layers, the main volume of the crystal and beam divergence. It is experimentally proved that if there are surface deformed layers, the structure of reflexes (thin lines, straight and figured lines of central part) depends on the beam divergence and the character of absorption and dispersion of X-rays by the deformed layers and the main volume of the crystal. It is shown that the presence of surface deformed layers is a necessary but not sufficient condition to form thin sidelines on the sectional topogram. Sectional topograms from both thin and thick step crystals have been obtained with polished surfacs of entrance and exit. It is established that thin lines on sectional topograms are the result of kinematic dispersion of X-rays in the surface deformed layers, and the middle wide line (the main reflex) is the result of dynamic dispersion in the main part of the crystal. The reduction of the divergent diffractive beam has been investigated with the help of asymmetrically carved crystal-monochromator working on reflection, and also the increase in the distance between the focus of the X-ray tube and the studied sample. It is shown that even in the case of big expositions, thin lines are absent on the topograms, the wide component of dynamic dispersion is too black. It is experimentally proved that for forming thin sidelines of reflex due to the surface disturbed layers, the divergence of the primary beam is a necessary condition.