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Only electrons scattered at small angles and without loosing energies will contribute to the information in the HRTEM images while all the others (which have lost energy and have been scattered multiple times or at high angles) also contains important information about the sample, they will for instance give a diffuse background in the images and benefit to EFTEM elemental mapping.
The coherent low angle elastic scattering can provide information of the relative position of atoms in the TEM specimens and is widely applied in diffraction techniques and HRTEM imaging. The combination of low angle elastic scattering with inelastic scattering can also provide the information of Kikuchi bands.
In TEM imaging, bright-field pictures are usually obtained at smaller angles and consist of a mixture of elastic, thermal diffuse, and inelastic scattering. When sample thickness exceeds few inelastic mean free paths (e.g. few hundreds of nanometers), the contribution of inelastic scattering dominates.
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