Comparison of different models for the generation of electron backscattering patterns in the scanning electron microscope

An electron backscattering pattern (EBSP) is formed on a fluorescent (or ot her) screen from the faster scattered electrons when a single-crystal regio n of a solid sample is illuminated by a finely focused electron beam (EB). The EBSP is very similar in appearance to the electron channeling pattern ( ECP) that is obtained in the scanning electron microscope (SEM) by rocking the beam about a point on the surface of a single crystal. It has been sugg ested that the mechanisms that give rise to EBSP and ECP are related by rec iprocity. If this is indeed the case, then the models that are used to expl ain them should be the same except for the direction in which the electrons travel through the specimen. The two-event "diffraction model" for EBSP (d iffuse scattering followed by diffraction) fails this condition, leading to the conclusion that the "channeling in and channeling out" model for EBSP is more likely to be correct. This has been described rigorously by Reimer (1979, 1985). It is named after the title used by Joy (1994). An attempt is made here to describe this model in a simple way.