TEM (transmission electron microscope) specimens can be damaged by the high-energy electron beam during observation. Therefore, it is important to recognize the effects of damage produced by the beam in TEM. These damages can be studied by monitoring the change of crystalline morphology using electron diffraction or high-resolution imaging, or by the extraction of specimen thickness, chemical composition, or electronic states from the changes in EELS features.
An example is that nano-crystalline mineral ferrihydrite (FHY) is an electron beam sensitive material and will undergo internal atomic rearrangement when exposed to the electron beam in TEM or STEM measurements .
 Pan, Y., et al., Electron beam damage studies of synthetic 6-line ferrihydrite and ferritin molecule cores within a human liver biopsy. Micron, 2006. 37(5): p. 403-411.