Light element depth distribution by the intensity ratio of incoherent and coherent scattering

A method is proposed for analyzing the distribution of elements with a small atomic number Z < 9 over the depth of the substrate. The method is based on measuring the ratio of incoherent and coherent scattering peaks intensities at different exit angles of X-rays from the sample surface. Varying the beam exit angle at a constant scattering angle makes it possible to vary the depth of radiation penetration into the sample by almost two orders of magnitude and, correspondingly, to vary the information averaging zone. Mathematically, the method reduces to the numerical solution of integral equations of the first kind, in which the impurity distribution profile is given by the model function. Experimental measurements were performed on model samples of beryllium (Z = 4) and aluminum (Z = 13) foils and real coatings of boron (Z = 5) and titanium nitride. The adequacy of the received solutions to the certified characteristics is shown.