X-ray Tube-based RIXS: Synchrotron-free Atomic Local Environment Determinations

PÉREZ R.D.; ROBLEDO, J.; LEANI J.; SÁNCHEZ H.J.

Córdoba

Simposio; 14th International Symposium on Radiation Physics-ISRP14; 2018

During the last few years, several works have been shown different applications of Resonant Inelastic X-ray Scattering (RIXS) for the discrimination, determination and characterization of chemical environments in a variety of samples and irradiation geometries. So far, this RIXS tool had been applied using synchrotron radiation facilities in an exclusive way, due to the main requirement of a monochromatic exciting beam and the convenience of the highflux. This work presents results of the first measurements of this novel RIXS tool for chemical characterization using a conventional X-ray tube source.The experimental experience was carried out at the Non-Conventional XRF Laboratory of the Atomic and Nuclear Spectroscopy Group at the National University of Córdoba, Argentina. The preliminary setup designed for these measurements is mainly composed by an X-ray tube (Mo anode), a Si(111) crystal as monochromator, a versatile sample holder, a couple of slits and a Si-pin diode X-ray detector AMPTEK-XR100T (180 eV @ Mn-Ka line, 3mm front leadcollimator). The studied samples were three pure compounds of iron: a steel, a Fe(III) (Fe2O3) and a Fe(II,III) (Fe3O4) oxide. Several RIXS spectra of each sample were acquired using an incident energy of ~7050 eV (i.e. below the Fe-K edge) in air atmosphere and in the conventional 45°- 45° geometry. RIXS peaks were analyzed by Multivariate Methods (as Principal Component Analysis (PCA)) in order to properly discriminate the fine structure of each spectrum. The PCA procedure revealed that the fine structure of each RIXS peak clearly depends on the studied compound. This result open the possibility of local environment characterization by means of RIXS using an energy dispersive system combined with a conventional X-ray tube. This promising RIXS tool, where synchrotron radiation is no needed, would offer an unique opportunity to study chemical states in different kinds of samples at a local X-ray tube based laboratory; characterization nowadays difficult or impossible to achieve by other methods.Taking into account these encouraging results, the next step consists in the improvement of the experimental setup, as a new channel cut monochromator, for the ulterior study of a variety of samples of interest by using the presented RIXS methodology.