Assessment for applicability of the "tangent technique" in X-ray small-angle scattering

A number of simple model systems are used to examine the applicability of the "tangent technique", employed in the small-angle X-ray scattering for estimating the particle size distribution function, as well as to ascertain the relative contributions of the scattering intensity by differently sized particles to the total scattering intensity. The undertaken analysis has shown that, even in the most favorable case-an ensemble of two groups of different-size particles-the "tangent technique" cannot be used either to find the particle size proper, or to ascertain the relative contributions of individual groups to the total scattering intensity.