Diffraction of fast H atoms during grazing scattering from an Al 2 O 3 (11 0) surface

H atoms with energies up to 1keV were scattered under a grazing angle of incidence from an Al2O3(112¯0) surface. After preparation of the target by annealing at a temperature of 1700°C well defined angular distributions for scattered projectiles are observed showing for scattering in the regime of axial channeling rich diffraction patterns. For scattering along the low indexed [1¯100] direction diffraction spots are arranged on a circle which is attributed to full coherence preserved during the collision with the surface. By an azimuthal rotation of the target surface by some degrees Laue circles of higher orders can be observed which is accompanied with a substantial enhancement of resolution for periodicity intervals of the target surface. This is demonstrated by results for the (12×4) phase of the Al2O3(112¯0) surface which indicate an overall transfer width for fast atom diffraction of several 100Å.