Electron energy loss spectroscopy investigation through a nano ablated uranium dioxide sample

A lamella of uranium dioxide (∼10×∼10×∼0.02–0.20 μm) was produced by focused ion beam for transmission electron and electron energy loss spectroscopy (EELS) examinations. This sample allows quantitative analysis of the EEL spectra recorded for UO2 as a function of the thickness. The M, N, O and P edges were recorded over zero loss to 4000 eV loss. The edges allow reconstruction of the electronic transitions, the lowest energy loss edges for P transitions corresponds to P3 electron transition (17.2 eV) from U6p3/2 level. The edge analysis allows also better interpretation of the loss spectrum with identification of the plasmon peak of the core electron transition edges. In addition, the energy lost was studied through a range of thicknesses going from ∼20 to ∼200 nm to derive the electron mean free path and cross section for inelastic scattering in the plasmon part of the spectrum. The mean free path of inelastic electron for uranium dioxide is compared with that reported earlier for other oxides from Be to Bi and for 200 keV incidents electrons. The present study emphasises the potential of combining FIB and EELS for the analysis of actinide compounds.