X-RAY RESONANT RAMAN SCATTERING EXTENDED FINE STRUCTURE

JUAN JOSÉ LEANI; H.J. SÁNCHEZ; D. PEREZ; C.A. PEREZ

Campinas

Congreso; RAU XXIII; 2013

Laboratorio Nacional de Luz Sincrotron

When X-ray photons irradiate atoms under resonant conditions, a low probability interaction can arise: the X-ray resonant Raman scattering (RRS). This inelastic process presents some relevant differences compared to other interactions between X-rays and matter; when the exciting photon energy approaches from below to an absorption edge of a target element, the Raman process become dominant over other effects. In a X-ray Raman process for an incident photon energy a variety of emitted photon energies are possible, contrasting, for example, florescent process where the emitted photon has a fixed energy. In this work we study the oscillations present in the RRS fine structure of diverse metal compounds. In order to understand and explain these oscillation patterns, we also isolated the oscillations of different EXAFS spectra. After a simple data manipulation, a direct comparison between the oscillation of both RRS and EXAFS experiments was performed. A notable similitude between both patterns is present in all the studied compounds. The experiments were carried out at the XRF Beamline of the Laboratorio Nacional de Luz Sincrotron (LNLS) of Campinas, Brazil. For the first time interference information, i.e. EXAFS modulations, has been observed in X-ray scattering spectra using a low resolution EDS system. These results suggest a new spectroscopy technique allowing chemical charac- terizations using X-ray Raman scattering. In this regard, first results had shown the potentiality of these kinds of experiments. Additionally, due to the adaptability of emission techniques, several possibilities appear from the applications of RRS spectroscopy in different geometries, as in grazing incident conditions for surface studies and even three-dimensional analysis by RRS in confocal arrangements. In these cases, this new tool could obtain meticulous 3D spatially resolved information about constitutive elements and their oxidation states; information not viable to achieve using conventional absorption techniques. This novel RRS chemical-environment technique will offer an excellent oppor- tunity to study diverse kind of samples in the micro- and nano-regime using a low resolution system.