Time-Resolved Energy Dispersive Inelastic X-ray Scattering (TR-EDIXS) for fast chemical state investigations

SÁNCHEZ, HÉCTOR JORGE; JUAN JOSÉ LEANI; JOSE ROBLEDO

Girona

Conferencia; International Conference on Total Reflection X-Ray Fluorescence Analysis and Related Methods (TXRF2019).; 2019

Universidad de Girona

EDIXS makes use of core-level Resonant Inelastic X-ray Scattering (RIXS), taking advantage of the benefits of an energy dispersive detection system and multivariate methods for the data analysis. As result, this novel methodology presents a fast acquisition, energy-scanning free experiments, low self-absorption effects and an objective interpretation of the data. By the application of EDIXS, the local chemical environment of an element of interest can be characterized in a variety of experimental conditions [1].Due to the latest developments on X-ray sources (as pulsed ones) and the possibility of controlling the environmental conditions of a sample (as temperature, pressure, atmosphere, etc.), the need of a practical technique for a fast characterization of chemical environments is evident. In addition, the study of some system evolutions requires a fast and sensitive spectroscopic tool, in order to properly understand the process dynamics.This work presents results of EDIXS analyzing its performance for time-resolved characterizations.A nanometric sample consisted of a pure Cu foil, deposited on a silicon wafer, was measured in the XRF-D09B beamline [2] at the Brazilian Synchrotron Light Laboratory (LNLS, Brazil) in total reflection conditions. The sample was excited with photons having energy below the Cu-K absorption edge. Thirty RIXS spectra were measured, with an acquisition time of 3 seconds per spectrum. During the measurements, the sample was allowed to oxidize by putting it in contact with an external heat source at ~ 400 °C.A Hierarchical Cluster Analysis (HCA) was carried out on the data before applying a Principal Component Analysis (PCA) procedure to the RIXS spectra.The result of the PCA procedure shows two well discriminated groups of measurements, differentiating the presence of two kinds of fine structures in the RIXS spectra, at a particular time interval. The separation of the same two clusters proposed by the HCA procedure supports this outcome.The successful results and the high sensitivity demonstrated for this technique, point out EDIXS as a promising technique for applying in studies involving fast changes in the chemical environment of an absorbing atom of interest. These chemical state determinations are achievable in the order of the seconds (or even less), being possible for in-situ characterizations as well, overcoming the limitation of the typical time-consuming absorption techniques.[1] J.J. Leani, J.I. Robledo, H.J. Sánchez, Spectrochimica Acta Part B 154, 10 (2019).[2] C.A. Pérez, M. Radtke, H.J. Sánchez, H. Tolentino, R.T. Neuenshwander, W. Barg, M. Rubio, M.I.S. Bueno, I.M. Raimundo, J.J.R. Rohwedder, X-Ray Spectrometry 28, 320 (1999).