Surface resonance channelling in scanning reflection electron microscopy
The phenomena of the channelling of electrons along planes or rows of atoms in the surface layers of crystals has been investigated recently in relation to microdiffraction and RHEED, REM, (reflection electron microscopy) and REELS (reflection electron energy loss spectroscopy) by using a conventional TEM in the reflection mode.The renewed interest in this phenomenon, known for many years, is the evidence from calculations of dynamical diffraction effect at surfaces that the electrons may be channelled along the topmost layers of atoms on a crystal surface and that the RHEED, REM and REELS signals may thus be sensitive to the structure and composition of the surface layer. These techniques may therefore provide a powerful new approach to the study of surfaces in which surface microanalysis and diffraction studies may be combined with nanometer-resolution imaging.An investigation has now been made of the analogous techniques which may be applied to the study of surfaces by use of a scanning transmission electron microscope.