 Crystallographic electron channeling

Crystallographic electron channeling is orientation-dependent propagation of electrons in a crystal, where the spatially ordered electrostatic potential changes how the beam travels relative to atomic planes or columns. Changing crystal orientation can therefore change the collected signal even without changing chemical composition.

A small specimen tilt at fixed beam energy is a useful test: brightness changes correlated with orientation suggest a channeling or electron diffraction contribution. This matters when interpreting backscattered-electron atomic-number contrast or atomic-scale chemical maps. A bright region is not by itself proof of a different atomic number.