DIRECT EVIDENCE FOR TERRACE BENDING FROM HE BEAM SCATTERING ON PT(997)

He-nozzle beams (λ = 0.56 A ̊A, S = (λ2/Δλ2) 1 2 ≃ 17) were scattered on a stepped Pt(997) surface. Diffraction peaks up to the 6th order are clearly resolved. For incident angles θi < 65°, the diffraction patterns are very similar to the patterns obtained by light scattering on echellette gratings. An elementary model based upon this analogy fits the results fairly well. The deviations observed for glancng angles of incidence are interpreted as an evidence for an upward bending of the interaction potential on the terrace in the vicinity of the downward step. © 1979.