Study of the Oxidation State by Comparative Analysis of Resonant Raman Inelastic X-Ray Scattering Emission

H. J. SÁNCHEZ; M.C. VALENTINUZZI; J. J. LEANI; C. A. PÉREZ

Campinas

Congreso; RAU XX; 2010

LNLS

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 (RRS). In this process, the emitted photons have a continuous energy distribution with a high energy cut-off limit. In the last few years experiments of RRS has become a very powerful technique to investigate excitations of electrons in solids. This work presents results regarding the possibility of determining the oxidation state by resonant Raman scattering using an energy dispersive system. Several measurements of samples of Mn, Fe, Cu and theier oxides were carried out, using monochromatic synchrotron radiation at the XRF beamline of the LNLS (Campinas, Brazil), below and close to their absorption edges to inspect the RRS emissions. The spectra were analyzed with specific programs for fitting the experimental data to theoretical expressions. After that, residuals were determined in the low energy side of the RRS peaks and a FFT smoothing procedure was applied, taking into account the instrument functions of the detecting system. The results show an oscillation pattern that depends on the sample, i.e. on the oxidation state, being a possibility of chemical speciation determination using RRS spectroscopy. The changes in the RRS structure between the pure elements and their oxides are discriminated and suggest the possibility of structural characterization by means of resonant Raman scattering using an energy-dispersive system combined with synchrotron radiation.   More measurements in different samples will be carried out to verify the present results and to establish a repetitive and reliable method of structural determination.  Acknowledgements: This work was partially supported by the LNLS (Campinas. Brazil).