INVESTIGADORES
SANCHEZ Hector Jorge
congresos y reuniones científicas
Título:
X-RAY RESONANT RAMAN SCATTERING EXTENDED FINE STRUCTURE
Autor/es:
J. J. LEANI; H. J. SÁNCHEZ; R.D. PÉREZ; C. A. PÉREZ
Reunión:
Congreso; RAU XXIII; 2013
Resumen:
When X-ray photons irradiate atoms under resonant conditions, a low probability
interaction can arise: the X-ray resonant Raman scattering (RRS). This inelastic
process presents some relevant differences compared to other interactions between
X-rays and matter; when the exciting photon energy approaches from below to an
absorption edge of a target element, the Raman process become dominant over
other effects. In a X-ray Raman process for an incident photon energy a variety of
emitted photon energies are possible, contrasting, for example, florescent process
where the emitted photon has a fixed energy.
In this work we study the oscillations present in the RRS fine structure of diverse
metal compounds. In order to understand and explain these oscillation patterns,
we also isolated the oscillations of different EXAFS spectra. After a simple data
manipulation, a direct comparison between the oscillation of both RRS and EXAFS
experiments was performed. A notable similitude between both patterns is present
in all the studied compounds.
The experiments were carried out at the XRF Beamline of the Laboratorio
Nacional de Luz Sincrotron (LNLS) of Campinas, Brazil.
For the first time interference information, i.e. EXAFS modulations, has been
observed in X-ray scattering spectra using a low resolution EDS system.
These results suggest a new spectroscopy technique allowing chemical charac-
terizations using X-ray Raman scattering. In this regard, first results had shown
the potentiality of these kinds of experiments. Additionally, due to the adaptability
of emission techniques, several possibilities appear from the applications of RRS
spectroscopy in different geometries, as in grazing incident conditions for surface
studies and even three-dimensional analysis by RRS in confocal arrangements. In
these cases, this new tool could obtain meticulous 3D spatially resolved information
about constitutive elements and their oxidation states; information not viable to
achieve using conventional absorption techniques.
This novel RRS chemical-environment technique will offer an excellent oppor-
tunity to study diverse kind of samples in the micro- and nano-regime using a low
resolution system.