MICRODIFFRACTION AND STEM OF INTERFACES

The techniques which have been developed for using very fine electron beams for the study of solid-vacuum interfaces may be applied to solid-solid interfaces with some restrictions. The nanodiffraction patterns obtained with the electron beam parallel to the interface may show that refraction effects and the extra spots due to surface channeling, and corresponding effects may be expected in high resolution images. The contributions of interface energy states to EELS spectra will be more difficult to detect. The images of features of interfaces not parallel to the incident beam which are most directly interpretable should be the dark-field STEM images obtained by detecting all the diffuse scattering outside of the main spots of the microdiffraction pattern. To a reasonable approximation the image intensities should be given by the convolution of the intensity distribution of the beam incident at the feature and the scattering power of the feature itself.