CONICET | Buscador de Institutos y Recursos Humanos

X-ray fluorescence spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower and close to an absorption edge, scattering peaks appear due to an inelastic process known as resonant Raman scattering. It constitutes an important contribution to the background of the fluorescent line. The Resonant Raman Scattering must be taken into account in the determination of low concentration contaminants, especially when the elements have proximate atomic numbers. The values of the mass attenuation coefficients experimentally obtained when materials are analyzed with monochromatic X ray beams under resonant conditions differ from the theoretical values (between 5% and 10%). This difference is due, in part, to the resonant Raman scattering. In this work we present theoretical calculations of the resonant Raman scattering contributions to background of X-ray fluorescence spectra. In order to perform the calculations the Shiraiwa and Fujino´s model was used to calculate characteristics intensities and the different scattering interactions. This model makes certain assumptions and approximations to achieve the calculations, especially in the case of the geometrical conditions and the incident and takeoff beams. Nevertheless the calculated data show a good agreement with previous results. The calculations show (among many other results) that the resonant Raman scattering prevails over Compton scattering in several ranges of energies but its contributions is lower than coherent processes. The model proposed here allows analyzing the different sources of background, which contribute to a better understanding of the physical processes involved in the different techniques of XRF analysis.