Analytical features of the Soller X-ray optical scheme

A theoretical expression for calculating the profile and intensity of an X-ray spectrum line measured by using the Seller X-ray optical scheme (XROS) is obtained. The formula proposed makes it possible to calculate the dependence of the XROS resolution and luminosity on the parameters of a multiplate collimator and characteristics of the analyzer crystal. It is shown that the most correct expression for estimating the XROS energy resolution is Delta E = E cot theta root delta theta(cr)(2) + (b/l)(2), where E is the line energy, theta is the Bragg angle corresponding to this line, delta theta(cr) is the analyzer crystal mosaicism, and b and l are the distance (gap) between the collimator's plates and their length, respectively. Calculations are presented that allow us to assert that the effect of superposition of an adjacent interfering line on the line under analysis in measurements with crystal-diffraction equipment is much weaker than with energy dispersive devices, even with a comparable energy resolution.