ENERGY-FILTERING IMAGING AND DIFFRACTION

Energy-filtering transmission electron microscopy (EFTEM) can combine the modes of electron spectroscopic imaging (ESI) and electron spectro scopic diffraction (ESD), and different modes can be used to record an energy-loss spectrum. ESI allows to remove the inelastically scattere d, electron in the zero-loss mode and to investigate thicker foils. Pl asmon-loss filtering can be used to separate different phases which di ffer in their position of the plasmon losses, for example. Elemental m aps can be calculated with micrographs taken below and beyond an ioniz ation edge. The modes of contrast tuning or most-probable-loss imaging at higher energy losses of a few hundreds of electronvolts can be app lied to very thick foils which cannot be investigated in a conventiona l TEM. ESD also allows to remove the background of inelastically scatt ered electrons in diffraction patterns of amorphous, polycrystalline a nd single-crystalline materials by zero-loss filtering. Increasing the selected energy loss can separate the different contributions by ther mal-diffuse scattering, inelastically scattered electrons and Kikuchi bands. The filtering of convergent-beam electron diffraction patterns allows a much better determination of the Fourier coefficients of the lattice potential and a calculation of charge-distribution maps. This review summarizes the possibilities of EFTEM for applications in mater ials science.