3D- Identification of Oxidation States by Means of Resonant X-Ray Scattering

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

Rio de Janeiro

Congreso; International Symposium on Radiation Physics (ISRP 2012); 2012

Universidade Federal do Rio de Janeiro

Micro X-Ray Fluorescence (μXRF) analysis is one of the latest branches of XRF. This spectroscopic technique has been quickly developed mainly due to the use of synchrotron facilities. Since nowadays 3D-mapping becomes viable in micrometer regime, μXRF is a established analytical method in a variety of fields. This technique was opened up by the arrival of new X-ray optics, especially by the improvement of capillary optics. In the last few years, accurate quantification procedures 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 one of the most serious limitations of this technique. Recently, it has been successfully employed X-ray Raman scattering spectroscopy to determine oxidation states of metals. We present results showing 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 depth scanning was carried out in a Cu-multilayer sample at the Brazilian synchrotron using a confocal arrangement. The sample was irradiated with monochromatic photons having energy close but lower than the Cu-K absorption edge. The X-ray Raman peaks were analyzed with specific programs for fitting the experimental data to theoretical expressions. After a simple data treatment, the results show an oscillation pattern that depends on the oxidation state of Cu. The results allow the discrimination of the oxidation state of the elements present in a sample in a 3D-micrometer regime by means of X-ray Raman scattering combined with a confocal setup. Additionally, the result could be used as a tool to determine the dark matrix present in a sample with the aim of establishing 3D-μXRF as a complete analytical technique.