IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Depth Analysis of Chemical Environments using Resonant Raman Spectroscopy in Total Reflection Geometry
Autor/es:
LEANI J.; H.J. SÁNCHEZ; PEREZ, R.D.; C.A. PÉREZ
Lugar:
Campinas
Reunión:
Workshop; XXII Reunião Annual de Usuários. Laboratório Nacional de Luz Síncrotron; 2012
Institución organizadora:
Brazilian Synchrotron Light Laboratory
Resumen:
Total Reflection of X-rays is a largely proved spectroscopic technique that allows the study of material surfaces. 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. Both total reflection and resonant Raman scattering techniques are used combined with the aim of discriminate oxidation states in nano-layers of materials. Samples of pure Cu and Fe oxidized in water and salty water, respectively, were studied in the Brazilian synchrotron using monochromatic radiation and an energy dispersive setup. The measurement were carried out in total reflection geometry scanning the incident radiation angle around the critical angle with incident energy lower and close to the K absorption edge of both elements in order to study the RRS emissions. For the first time, both resonant Raman scattering and total reflection techniques are used combined as a hybrid tool allowing discrimination of oxidation states in nano-layers of materials using a low resolution spectrometer. The main contribution of this article relies on the possibility of obtaining structural information with nanometric resolution, or even mstrongs, by using a typical energy dispersive setup. In this way, a lot of possibilities appear from the combination of RRS spectroscopy with other X-ray techniques, even threedimensional analysis by RRS combined with confocal setups. Currently, further investigations are carried out in order to reach a complete understanding of the processes involved with the aim of turn this practical method into a true and complete analytical tool.