2. Channelling electrons

It is the channelling of electrons that is responsible for the orientation contrasts observed in BSE micrographs, as illustrated in figure 3 . The yield of backscattered electrons depends on several factors, including the topography of the observed zone, the presence of different phases through the average atomic number Z of the phase, and finally the orientation of the crystal with respect to the electron beam. If the observed zone consists of a single phase, and if its surface is perfectly polished or has very low native roughness, then the predominant parameter influencing the BSE contrast is the orientation of the crystal with respect to the...