Theoretical Calculations of Resonant Raman Scattering contributions to XRF Spectra

HÉCTOR JORGE SÁNCHEZ; MARÍA CECILIA VALENTINUZZI; JUAN JOSÉ LEANI

Rio de Janeiro, Brasil

Congreso; SARX 2008; 2008

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 kown as 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 Shirawa and Fujino´s model was used to calculate characteristic 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 take off beams. Nevertheless the calculated data show good agreement with previous results. The calculations show that the resonant Raman scattering prevails over Compton scattering only in the lower region of energy, far away from the fluorescence region, dominating the Compton dispersion in the rest of the range. The calculated reinforcement proves to be weak and has influence only in the spectra of lightest elements. 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.