Light elements quantitative x-ray microanalysis of thin samples in STEM. Absorption correction using EELS data

Abstract

Quantification of low Z elements like oxygen by energy-dispersive x-ray spectrometry requires x-rays absorption correction even the in the case of thin films analysis in scanning transmission electron microscope. Absorption correction needs the knowledge of the sample local mass thickness. The purpose of this paper is to propose a method which allows the obtainment of the sample local mass thickness and then permits the quantification of all the elements of the sample using the quantification ratio method. Combining electron energy loss spectroscopy measured relative specimen thickness, and x-rays characteristic peaks intensities, we determine with an iterative process the local mass thickness and the absorption corrected elemental weight concentrations. We validate our method with four standard samples (SiO, SiO2, CaSiO3 and Li4SiO4) by the determination of the O/Si atomic ratio. We also ensure the method by analysing a native bioactive glass sample of known composition and of inhomogeneous mass thickness.