IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
OXIDE NANO-LAYERS STUDIED BY X-RAY RAMAN SCATTERING IN TOTAL REFLECTION GEOMETRY
Autor/es:
JUAN JOSÉ LEANI; H.J. SÁNCHEZ; C.A. PEREZ
Lugar:
Campinas
Reunión:
Congreso; Annual User´s Reunion (RAU) of the Luz Synchrotron National Laboratory (LNLS) 2013; 2013
Institución organizadora:
LNLS
Resumen:
Different processes could take place from the interaction of X-ray with matter: photons can be absorbed by the photoelectric effect and decay in florescence process, the photons could also experience coherent or incoherent scattering. Nevertheless, under resonant conditions, another low probability interaction can occur: the x-ray resonant Raman scattering (RRS) [1]. If the angle of the incident radiation is less than a critical angle derived from the Snells law, X-rays are totally reflected due to the refractive index is less than unity [2]. Making use of this fact, different depths of a sample can be studied scanning the incident photon angle through this critical angle. At this respect, studies of characteristic emissions, or reflected intensities, present a tool for the analysis of surface properties, such as variations of electron density with depth with resolutions from ngstr¨oms to microns [3]. This work shows experimental results of X-ray Raman scattering at grazing incidence conditions with the aim of recognize chemical environments in different layers of stratified materials using a low resolution energy dispersive system. Multilayer samples of Fe compounds were measured in the XRF beamline of the Brazilian synchrotron facility using monochromatic radiation and an EDS setup. The measurements were performed in total reflection regime with incident photon energy lower and close to the K absorption edge of Fe. After a simple data processing, the result allowed characterizing oxide nanolayers, not observable with the use of conventional geometries, reaching identification of the oxidation state present in a particular depth of a sample surface with nanometric, or even sub-nanometric, resolution using a low-resolution EDS system.