New Trends for Spatially-Resolved Micro-Raman Spectroscopy. 3D Reconstruction of Thickness and Oxidation State Distribution of Stratified Samples

LEANI J.; H. J. SÁNCHEZ; PEREZ, R.D.; C.A. PÉREZ

Campinas

Congreso; 21st edition of the International Congress on X-Ray Optics and Microanalysis (ICXOM); 2011

Brazilian Synchrotron Light Laboratory

3D-micro X-ray fluorescence spectroscopy (3D Micro-XRF) enables non-destructive threedimensional investigation of elemental distribution in samples in the micrometer regime. A remarkable field of application of this technique is the investigation of stratified materials. In the last few years, quantification procedures reasonably accurate have been developed. The most important problem in these quantification procedures is the existence of light elements in the sample from which no fluorescence is detected. This “dark matrix” problem is not yet solved and is now the most serious limitation of this technique. In this work we present first results regarding the possibility of determining the oxidation state of an element, in a three-dimensional regime, by resonant Raman scattering using an energy dispersive system combined with a confocal setup. A 3D scanning of a multilayer sample in confocal setup was carried out in the XRF Beamline of the LNLS (Brazil). The sample consisted of an arrangement of 3 layers with different diluted Cu oxides each, over a glass substrate. The sample was irradiated with monochromatic photons having energy close but lower than the K absorption edge of Cu. The Raman peaks 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. Finally, a FFT smoothing procedure, in order to take into account the instrument functions of the detecting system, was applied. The results show an oscillation pattern that depends on the oxidation state of cooper. The result is relevant since allows the discrimination of the oxidation state of the elements present in a sample in a 3D-micrometer regime by means of resonant Raman scattering combined with a confocal setup. In addition, this result could be used as a tool to determine the dark matrix present in the sample with the aim of establishing a reliable quantification procedure. This knowledge is the precondition to render the 3D Micro-XRF spectroscopic method into a true and complete analytical tool.