Reflection electron microscopy of buried interfaces in the transmission geometry

We consider a thin film in TEM containing a vertical interface in the plane of the beam. The intensity of the specular beam reflected from the interface is considered under multiple scattering conditions. For an atomically abrupt (100) interface between Au and MgO, this beam is found to have appreciable intensity, comparable to the (000) beam, at a certain thickness. The wavefield corresponding to this reflection is confined to a narrow sheet at the interface if the Bragg condition is avoided. The formation of a reflection dark-field image of such an internal interface is discussed, for the purpose of observing interface reactions at high temperature. The use of an imaging energy filter fitted to a high voltage microscope is proposed for this purpose. The use of this specular reflection for microanalysis by energy loss spectroscopy and the study of interatomic bonding at interfaces is also suggested.