Imaging of surfaces by means of secondary electrons

Secondary electrons emitted from crystal surfaces show a strong enhancement of intensity along directions defined by atomic rows. The gross features of such patterns are formed by the projection of surface layers illuminated by an internal source of electrons. The patterns reveal crystallographic directions and planes at atomic resolution. While the strongly forward-peaked electron-atom scattering is responsible for the observed symmetry, these secondary electron diffraction (SED) patterns also contain features due to Bragg-like diffraction at interatomic planes.