COMPARISON OF CALCULATION METHODS FOR SECTIONS OF DISPERSION IN X-RAY SPECTRAL REGION
Coherent and non-coherent dispersion of the x-rayed photons on atoms, molecules and solid body at subzero energies of photons (less than 60 keV) is an important instrument for the receipt of information about structural properties of materials and their chemical composition. In the real work comparison of results of calculations is conducted in differential coefficients of coherent and non-coherent dispersion of different approaching with experimentally measuring. Calculations are executed in the form-factorial approaching (FF) without (MFF) and with taking into account anomalous dispersion (ASFs); on approximation equalizations of atomic form-factors and non-coherent function of dispersion for the wide field of numbers of chemical elements and parameter; on the program Xraylib, in that approximation is used the cube splines of quantum-mechanical calculations, and also on close formulas based on Thomas Fermi method. Calculations and experimental measuring are conducted for dispersion of photons with energy 22.1 keV, that corresponds to the characteristic line of Ag K α on elements with atomic numbers 6 < Z < 81 and angle of dispersion 133º. The quantitative estimations of difference of the expected values of sections of dispersion and measured are got. Values are specified by permanent screening in a close formula for the calculation of coefficient of coherent dispersion. A value is specified by permanent screening in a close formula for the calculation of coefficient of coherent dispersion. It is shown that change of value permanent screening from 2 to 0.3 notably improves convergence of results of calculation with an experiment. It is turned out that the calculations of sections for multielectronic atoms (large Z ) give the most divergences with the results of experiment.