Fundamental parameters approach in tube‐excited secondary target XRF set‐ups: comparison between theory and experiment

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AbstractAlgorithms utilizing the fundamental parameters approach (FPA) can be applied for the calculation of sample fluorescence intensities in tube‐excited secondary target x‐ray fluorescence (STXRF) set‐ups. The results of such calculations have recently been presented in the literature for different combinations of anode materials‐secondary targets over a wide range of operational voltages. In this work, the accuracy of the FPA was thoroughly tested through the comparison of theoretical results with experimental data obtained by a series of measurements performed in an Mo anode tube–secondary target XRF assembly. The comparison shows that the FPA describes fairly accurately the dependence of experimental fluorescence intensities as a function of the operational voltage. However, the accuracy depends on the model used for the description of the tube spectral distribution and the position of the secondary target K‐absorption edge with respect to the energy of the anode characteristic lines and the high‐voltage cut‐off limit. Furthermore, our experimental data indicate that the analytical models used in this work to reproduce the Mo anode emission spectra at different operational voltages predict rather unsatisfactorily the distribution of continuum radiation near the high‐voltage cut‐off limit. The methodology adopted in this work may be considered also as an indirect way for testing the validity of x‐ray tube spectral distributions in certain energy regions. Copyright © 2004 John Wiley & Sons, Ltd.