Most analytical microscopes are equipped with energy loss spectrometers capable of giving spectra showing 1-2 eV resolution for inner shell edges. The relatively weak modulation starting 30-50 eV from threshold due to Extended X-ray Edge Energy Loss Fine Structure (EXELFS) which is analogous to EXAFS in X-ray absorption has been studied in some detail. Although the theory is, in principle, straightforward the technique using energy loss in the electron microscope to determine nearest neighbour distances has not attracted widespread interest. This is partly due to the long counting times involved. The near edge structure (NES) within 20-30 eV of threshold is characterized by a very strong modulation and is clearly visible even when small amounts of the element are present. Interpretation of the features is very much more difficult and except in those cases in which peaks can be clearly assigned to transitions to antibonding orbitals the main form of analysis has been limited to simple comparisons or fingerprinting.
Core-hole effects on theoretical electron-energy-loss near-edge structure and near-edge x-ray absorption fine structure of MgO
