Depth Analysis of Chemical Environments using Resonant Raman Spectroscopy in Total Reflection Geometry

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

Campinas

Otro; Turno de medición; 2011

Total Reflection of X-rays is a largely proved spectroscopic technique that allows the study of material surfaces. As the refractive index is less than unity, X-rays incident on a material are, theoretically, totally reflected if the glancing angle is less than a critical angle derived from the Snell´s law. Making use of this phenomenon, different depths of a sample surface could be studied by means of the correct election of the incident radiation angle. In this way, analysis of the reflected intensity could provide a method for studying surface properties, as variations of electron density with depth (e.g., corrosion, porosity, aging, etc.) with a resolution from Amstrongs to hundred nanometers deep. X-ray resonant Raman scattering (RRS) is an inelastic scattering process which presents fundamental differences compared to other scattering interactions between X-rays and atoms; when the energy of the incident photon approaches from below to an absorption edge of the target element, a strong resonant behavior takes place. Both total reflection and resonant Raman scattering techniques are used combined with the aim of discriminate oxidation states in nano-layers of materials.