Fast H, He atoms, and H2 molecules with projectile energies ranging from 200 eV up to 3 keV were scattered under a grazing angle of incidence from a clean and flat β-Ga2O3(100) surface. The bulk single crystal was grown by the Czochralski method and prepared via annealing under ultra-high vacuum conditions. For scattering along low-index directions, we observed defined diffraction patterns in the angular distributions for scattered projectiles. From the analysis of diffraction patterns, we derive the surface unit cell in good accord with the parameters b and c for the lattice of the bulk crystal and derive information on the termination of the surface.

We have studied structures of the chiral amino acid alanine adsorbed on Cu(110) via low-energy electron diffraction (LEED) as well as scattering of fast light atoms and molecules. The adsorption process was controlled in situ by the intensity of specularly reflected 2-keV He atoms. For projectile energies less than 1 keV, we applied the method of fast atom diffraction for studies on the structure of adsorbed alanine molecules on an atomically flat Cu(110) surface with focus on a p(3 x 2) adsorbate phase. The results are consistent with LEED and explain distortions in LEED patterns via an elongated surface unit cell with incommensurate c(3.16 x 2) symmetry of parts of the adsorbate. From triangulation using fast atoms via the azimuthal rotation of the target surface, the positions of protruding methyl groups are derived.

H atoms with energies up to 1 keV were scattered under a grazing angle of incidence from an Al2O3 (11 (2) over bar0) surface. After preparation of the target by annealing at a temperature of 1700 degrees 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) over bar 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 x 4) phase of the Al2O3(11 (2) over bar0) surface which indicate an overall transfer width for fast atom diffraction of several 100 angstrom. (C) 2013 Elsevier B.V. All rights reserved.

We demonstrate that quantum scattering of fast atoms and molecules under grazing angles of incidence can be exploited to study the structure of organic molecules on metal surfaces. Making use of keV H and He atoms as well as H2 molecules, the surface structures of the chiral amino acid alanine adsorbed on a Cu(110) surface is studied. We present a detailed investigation on the (3×2) phase of a monolayer of enantiopure and racemic alanine on Cu(110), revealing the formation of an elongated surface unit cell of c(n×2) symmetry with n=3.16±0.04 for the sticking out methyl groups of the alanine molecules.

The structure of the topmost layer of thin V 2 O 3 films on a Au(111) substrate is studied via Ion Beam Triangulation. From electron emission induced by fast H atoms scattered from the film surface under a grazing angle of incidence as function of azimuthal rotation of the target, we find evidence for a reconstructed O 3 termination as proposed from DFT-calculations and recent experimental work using methods based on large angle impact of fast ions. From our studies we derive detailed lateral positions for the topmost O atoms.

Angular distributions for grazing scattering of keV H atoms from an Al2O3(11 (2) over bar0) surface were recorded. These distributions reveal defined diffraction patterns which can be understood in terms of quantum scattering from well-ordered surfaces. From the observation of so-called Laue circles, we conclude a high degree of longitudinal coherence for fast atom diffraction at surfaces which allows one to resolve periodicity intervals of several 100 angstrom. We demonstrate this feature in scattering experiments from the reconstructed (12 x 4) phase of an Al2O3(11 (2) over bar0) surface obtained after annealing at temperatures of about 2000 K. DOI: 10.1103/PhysRevB.86.241402