Méthodes d’analyse par fluorescence X au moyen des radioisotopes

Abstract

X-ray fluorescence analysis is carried out by exciting the inner energetic levels of the atoms (K, L levels) and measuring the intensities of the characteristic X-ray lines emitted by the elements to be analyzed.
Excitation is generally obtained by means of X-rays or accelerated electrons from generator tubes. These techniques are being developped intensely. But it is also possible to use radioactive sources emitting α, β⁻ or photons.
Interesting features of the use of radioactive sources are: stability of the exciting spectrum, small size, cheapness, availability of a large variety of spectrum shapes and sources. They are used in portable apparatuses and are particularly attractive for continuous control. However, because of their low intensity, it is not possible to analyze accurately the radiations emitted by the irradiated samples. It is necessary to use methods other than diffraction to determine the intensities of the K and L X-ray lines. So they are mainly used to determine the content of known elements in matrixes of relatively stable composition. They can also be applied to the solution of more complex problems.
Various techniques using radioactive sources have been proposed. A number of industrial applications is already made.
By their contribution to automatisation, these radioactive techniques have a large interest for the near future.