Comparative analysis of the resonant Raman cross sections of pure samples and oxides

MARÍA CECILIA VALENTINUZZI; HÉCTOR JORGE SÁNCHEZ; JOSÉ ABRAHAM; CARLOS PÉREZ

X-RAY SPECTROMETRY

Año: 2008 vol. 37 p. 555 - 560

0049-8246

The x-ray resonant Raman effect takes places when atoms are irradiated with an incident energy lower and close to an absorption edge. This inelastic process can produce an important contribution to the background of the fluorescent line. The resonant Raman effect must be taken into account when samples of pure elements or constituted by elements with proximate atomic number are analyzed because this effect affects the determination of low concentration contaminants. The experimental values of mass attenuation coefficients differ from the theoretical values when materials are analyzed with monochromatic x ray beams under resonant conditions. The resonant Raman scattering is in part responsible for this difference. Monochromatic synchrotron radiation was used to study the Raman effect on pure samples of Mn, Fe and Cu and on oxides like Mn2O3, Fe2O3, CuO and Cu2O. Energy scannings were carried out in different ranges of energies near the absorption edge of the target element. Theoretical models for the energy distribution of the Raman scattered photons, convoluted with the instrument function, were used to determine the resonant Raman scattering cross-sections as a function of the incident energy. The results indicate that RRS cross-sections for pure samples are similar to those for oxides, showing that the Raman scattering takes place in the same way in both kinds of samples.