In this work two aspects of momentum-dependent electron energy loss spectrometry are studied, both in the core-loss and in the low-loss region. In the case of core losses, we focus on the demonstration and the interpretation of an unexpected non-Lorentzian behavior in the angular part of the double-differential scattering cross-section. The silicon L3 edge is taken as an example. Using calculations we show that the non-Lorentzian behavior is due to a change in the wavefunction overlap between the initial and the final states. In the case of low losses, we first analyze the momentum-dependent loss functions of coinage metals Cu, Ag, and Au. We then demonstrate how advanced electronic structure calculations can be used to build simple models for the dielectric function that can then serve as a basis for the calculation of more complicated sample geometries.

The behaviour of clays is not still well understood. Most information concerning clays has been obtained by techniques which give statistical information on the structure and chemistry. However papers have reported results from scanning and high resolution electron microscopy. This work presents a nanoscopic approach, using electron energy loss spectroscopy (EELS), of different purified clays. EELS permitted to detect all the elements found by classical chemistry at a macroscopic level. In particular it made it possible to determine the Si/Al ratio in kaolinite (Si/Al ~ 1), smectite and illite (Si/Al ~ 2). In all the cases, the K edge oxygen energy loss near edge structure (ELNES) is often similar to that of other clays we studied, but a strong heterogeneity has been observed. It was also possible to highlight an influence of the presence of iron on the profile of the oxygen peak.

EELS (electron energy loss spectrometry) in the transmission electron microscope (TEM) was used to determine the composition of a nanocrystalline magnetic specimen. The relative amounts of the hard magnetic phase Nd2Fe14B and the soft magnetic phase Fe3B at the point of measurement was measured by standard EELS quantification. In order to determine the structure of Fe3B present, the fine structure of the boron K-ionisation edge was analysed. Comparison of the experimental spectra with simulations of the fine structures based on the TELNES extension of the WIEN97 program package, a full potential linearised augmented plane wave approach to the calculation of electronic structure in crystals, shows that the tetragonal form of Fe3B is predominant.

High resolution electron imaging supported by computer image simulation has been carried out for a nominal “second–stage” NiCl2 graphite compound. The resulting local structure information underlines the statistical nature of the stage ordering, rarely perfectly regular. It also shows the interpenetration of differently staged regions.