Electron energy-loss spectroscopy (EELS) on nano-dimensional structures

The finely focused electron probe, down to a fraction of a nanometre in dia meter, delivered by the field emission source in a TEM column constitutes a very powerful tool for the local characterization of heterogeneous specime ns; It can be fixed, or rastered along a line or over a reduced area, and f or each beam position, several signals can be recorded simultaneously. In p articular, the parallel detector behind the velocity spectrometer provides EELS spectra covering a wide range of energies (from the eV-range to the ke V-range), which can be correlated with a high degree of spatial definition to well-defined features, e.g. surfaces, interfaces, dusters, nanoparticles . Beyond providing high-resolution chemical maps of various types of nanost ructures, this technique furthermore offers the possibility of exploring th e local electron excitation spectra. A detailed analysis of the variation o f these fine structures, e.g. across selected interfaces, is therefore show n to be very useful to evaluate the bonding properties at the apex of these interfaces. It will be demonstrated how such an advanced characterization tool at the atomic scale constitutes a necessary link between understanding the growth processes of nanostructures and tailoring their physical proper ties. Metal oxide systems (Pt-CeO2, NixFe(1 - x)-Al2O3, MgO-Cu) and mixed B CN nanostructures illustrate the most recent investigations.