Formation of X-ray fluorescence of elements with low atomic number

The approximation of monochromatic primary radiation was used to obtain reasonably straightforward expressions suitable for carrying out last estimating calculations of the contribution of photo- and and Auger electrons to the excitation of x-ray fluorescence. A dependence of this contribution on the energy of primary radiation quanta was calculated for single-element samples of boron and carbon, as well as for low carbon contents in the iron matrix. It was found that in the later case the ionization of carbon atoms by photo- and Auger electrons of the sample exceeds the photoionization of these atoms by about a factor of 50. Calculated results with data reported obtained on an earlier occasion for fluorescence excitation of atoms of elements with low Z by inhomogeneous radiation of the x-ray tube. Calculation showed that ionization of sample's atoms by photo- and auger electrons drastically changes the sensitivity of X-ray fluorescence of element with low Z to a variation of their content in analyte material and improves the accuracy of measurement of low contents of such elements. (author)