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

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

Campinas

Conferencia; IXCOM 21; 2011

LNLS

threedimensionalinvestigation of elemental distribution in samples in the micrometer regime. Aremarkable field of application of this technique is the investigation of stratified materials.In the last few years, quantification procedures reasonably accurate have been developed [1,2]. Themost important problem in these quantification procedures is the existence of light elements in thesample from which no fluorescence is detected. This “dark matrix” problem is not yet solved and isnow the most serious limitation of this technique [2].In this work we present first results regarding the possibility of determining the oxidation state of anelement, in a three-dimensional regime, by resonant Raman scattering using an energy dispersivesystem combined with a confocal setup.A 3D scanning of a multilayer sample in confocal setup was carried out in the XRF Beamline of theLNLS (Brazil) [3]. The sample consisted of an arrangement of 3 layers with different diluted Cuoxides each, over a glass substrate. The sample was irradiated with monochromatic photons havingenergy close but lower than the K absorption edge of Cu.The Raman peaks were analyzed with specific programs for fitting the experimental data to theoreticalexpressions. After that, residuals were determined in the low energy side of the RRS peaks. Finally, aFFT smoothing procedure, in order to take into account the instrument functions of the detectingsystem, was applied. The results show an oscillation pattern that depends on the oxidation state ofcooper.The result is relevant since allows the discrimination of the oxidation state of the elements present in asample in a 3D-micrometer regime by means of resonant Raman scattering combined with a confocalsetup. In addition, this result could be used as a tool to determine the dark matrix present in the samplewith the aim of establishing a reliable quantification procedure. This knowledge is the precondition torender the 3D Micro-XRF spectroscopic method into a true and complete analytical tool.