Concepts - introduction
The fundamental basis of electron microscopy is the use of an electron beam. It is for this reason that the TEM requires a vacuum. If air were present the molecules would cause the beam to scatter. It is also imperative to understand the interactions between the electron beam and the sample so as to interpret the resulting images. The use of electrons has an impact on image resolution and absence of colour, and explains the two dimensional nature of micrographs (images/photographs).