Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.80: Poster

Montag, 25. Februar 2008, 18:30–19:30, Poster F

Diffraction of fast atoms and molecules during grazing scattering from a LiF(001) Surface — •Andreas Schüller, Stephan Wethekam, and Helmut Winter — Humboldt-Universität zu Berlin, Institut für Physik, Newtonstraße 15, 12489 Berlin

Neutral atoms and molecules with energies from 300 eV up to some 10 keV are scattered under a grazing angle of incidence from a clean and flat LiF(001) surface. For scattering along low index directions in the surface plane ("axial surface channeling") we observe defined patterns in the intensity distributions for scattered atoms which can be attributed to diffraction effects [1, 2]. The data can be understood by diffraction of fast atoms at the surface where the symmetry of the crystal lattice and of the interaction potential between atom and surface determine the diffraction pattern. The periodicity of the surface potential follows the geometrical arrangement of surface atoms and determines the angular position of diffraction peaks. The corrugation of the surface potential determines the characteristic intensity modulations of these diffraction peaks which can be observed also for fast and for heavy atoms, where diffraction based on the periodicity of the crystal lattice can not be resolved. Such so called "supernumerary rainbows" allows one to derive the corrugation of atomic interaction potentials in the eV regime with high accuracy.

[1] A. Schüller, S. Wethekam, and H. Winter, Phys. Rev. Lett. 98, 016103 (2007).

[2] P. Rousseau, H. Khemliche, A.G. Borisov, and P. Roncin, Phys. Rev. Lett. 98, 016104 (2007).