THE OBSERVATION OF SURFACE RESONANCE EFFECTS IN RHEED PATTERNS

The surface resonance condition produces intensity anomalies in the Bragg reflections of RHEED patterns and also continuous parabolae and circles in the Kikuchi line patterns. An apparent doubling of the parabolae and circles results from the separation of the continuous curves from the envelopes of the straight Kikuchi lines. This separation is consistent with the idea that electrons channeled along lines or planes of atoms see an average potential different from that of the bulk crystal. Examples are given of diffraction from Pt, GaAs and InP surfaces.