Scattering of atomic beams off a single surface step: An exact solution

The scattering of atomic beams off a single rectangular step on a planar hard-wall surface is calculated exactly using the Wiener-Hopf technique. The diffuse scattering consists of a sharp peak around the specular direction which is due to interference effects between the two surface levels and which oscillates in magnitude with incident angle. A second part then describes a smooth background scattering which strongly depends on the actual shape of the step whereas the former does not. Since the step is an infinitely extended defect a finite part of the incident atoms is scattered into the peak around specular, in contrast to the case of a compact scattering object, where only an infinitesimal part is removed from the specular beam.