Estimates of detection limits for elements with atomic number 69 ≤ Z ≤ 92 in an Al matrix were obtained for Kα characteristic fluorescence excitation by Al braking target bremsstrahlung in a 5 MeV electron accelerator. The electron energy varied from 1 to 5 MeV. Relationships were obtained between detection limit and electron energy and between detection limit and atomic number of defined elements for an electron energy of 2 MeV. The results show that the chosen method of analysis makes it possible to determine heavy element concentrations down to 10−8–10−9%, which allows the solution of a great number of problems in ecology, geology, geochemistry and industrial technology for pure material production. Copyright © 2000 John Wiley & Sons, Ltd.

A probability method is used to describe the processes of characteristic x‐ray fluorescence excitation and absorption in a heterogeneous monolayer of particles. Based on this the analytical dependence of the characteristic x‐ray peak intensity on the sizes and shape of particles, and the distribution of elements among the particles is inferred, for two kinds of spectrum excitation. Theoretical evaluations for applying boundaries of the ‘thin’ homogeneous layer model to a heterogeneous monolayer are given. The elements to be determined in unknown compositions are S, Fe and Pb.

A set of particulate monolayer samples with a δ‐distribution of particle sizes has been produced on Lawsan membrane filters by means of a cascade impactor. The accuracy of a proposed equation for characteristic x‐ray intensity from particulate monolayers of various chemical and granular compositions has been experimentally confirmed. x‐ray spectra of Fe and PbTiO3 powders have been examined following excitation by monochromatic photons.