Resonant Ramam Scattering Effects on X-Ray Fluorescence Spectra

HECTOR JORGE SANCHEZ; M.C. VALENTINUZZI

Campinas (Brasil)

Congreso; RAU XV; 2005

The x-ray resonant Raman scattering[1] is an inelastic process that occurs when the energy of the incident x-ray photons is just below the absorption edge of an element. In the two-state model, a virtual K-hole is considered in the intermediate state to a final state with an L-hole (or M-hole) , an electron in the Fermi levels (or in the continuum) and a x-ray photon. Although the x-ray resonant Raman effect was first observed many years ago, there are relatively a few studies on it. A good determination of this effect is relevant because it contributes to the photoelectric absorption coefficient. Deviations between the measured values of mass attenuation coefficient and the corresponding theoretical ones of the order of 10% have been reported.[2] In addition, resonant Raman scattering can produce, under certain experimental conditions, unexpected peaks in x-ray fluorescence spectra. This work presents studies of x-ray resonant Raman scattering of different elements using monochromatic synchrotron radiation. Some transition elements and rare earths were irradiated with photons which energies were just below the absorption edge (K for metals and L for rare earths). Several energy scannings were performed to analyze the Raman peak (below the threshold), the energy of the absorption edge, and the fluorescent line (above the absorption edge) in order to determine the resonant Raman yield. Preliminary results agree very well with previous measurements reported by other autors. In addition, the analysis of different compounds of the same element did not show significant differences, on contrary to the speculations of some authors.