CRYSTAL LATTICE STUDIES USING ELECTRON CHANNELING PATTERNS.

Electron channeling patterns (ECP) permit crystallographic studies to be made of bulk samples in the scanning electron microscope (SEM) in the same way as diffraction patterns allow the examination of electron transparent crystals in the transmission electron microscope (TEM). The electron channeling contrast is a weak (typically 5%) modulation in the backscattered signal which occurs as the angle of incidence between the beam and the lattice planes is varied through deviations of the order of a Bragg angle. When optimum electron-optical conditions are set up patterns can be obtained at visual recording rates from areas as small as a few microns in diameter. The purpose of this review is to identify the origin of changes in pattern quality, to outline a method of quantifying these changes, and to illustrate, by means of applications, the kind of data that are available.