EELS is a powerful analytical tool for exploring the local solid state environment in materials. There is an extensive literature on EELS analysis of the transition elements and light elements, yet few EELS data exist for heavy elements with multiple oxidation states. We report here on EELS studies of oxidation state influences on near-edge structure in cerium and uranium compounds.

All materials analyzed for this study were embedded in low viscosity epoxy and TEM specimens prepared using ultramicrotomy. The thin sections (∼50 nm thick) were analyzed using a JEOL 2010 (200kV) TEM operated with a LaB6 filament and equipped with a GAT AN 666 parallel EELS spectrometer. EELS data were collected in image mode at 105X magnification with a collection semi-angle of ∼ 100 milliradians at a dispersion of 0.1 eV/channel. The full width at half maximum of the raw (unprocessed) zero-loss peak was 0.7 eV. Peak positions were calibrated by applying a known voltage to a drift tube.