Reflection and refraction of fast electrons at solid/solid interfaces

The combined effects of refraction and reflection of fast electrons entering a thin specimen nearly parallel to an interface may be used to obtain quantitative information about the difference in the mean inner Coulomb potential (U0) between the two adjoining phases. When no strong Bragg reflections are excited the electrons are deflected towards the phase with the largest vertical strokeU0vertical stroke. By tilting the crystal so that strong Bragg reflections are excited some of the Bloch waves may be deflected in the opposite direction. The effect is demonstrated by simple two-beam calculations and observations for the Al/SiC interface. (orig.)