1. Interactions between organic matter and electron beams

The two main types of microscope discussed here are the transmission electron microscope (TEM) and the scanning electron microscope (SEM).

In theMET , the image is formed by interactions between the sample and a large beam of electrons passing through it (figure 1 a ). It is then magnified by a system of electromagnetic lenses. Maximum separating power is of the order of 0.2 to 0.3 nm for modern medium-voltage TEMs (200 to 400 kV). Some TEMs also operate in scanning electron transmission microscopy (STEM) mode, with a very fine probe, which is useful, for example, if you want to combine morphology with spectroscopic analysis of the X-rays (RX) emitted during irradiation.