A. Schüller

Interaction potential for fast Ne atoms in front of LiF(001) surface

Fast Ne atoms with energies from 3 to 70 keV are scattered under a grazing angle of incidence from a flat and clean LiF(001) surface. For scattering along low-index directions (axial surface channeling) we observe pronounced peaks in the angular distributions of scattered projectiles which can be attributed to rainbow scattering. On the basis of classical trajectory calculations we derive from the rainbow angles the effective interaction potential of Ne atoms in front of LiF(001) and the underlying interatomic pair potentials in the eV energy range. Fair agreement with the data is found for individual pair potentials calculated from Hartree-Fock wave functions where the charge state of Li and F in the ionic crystal is taken into account.

Diffraction of fast atoms and molecules during grazing scattering from surfaces

Grazing scattering of light atoms and small molecules with energies up to several keV from atomically clean and flat surfaces along low-indexed directions gives rise to diffraction phenomena. The potential of this new method of Fast Atom Diffraction (FAD) as surface analytical tool is discussed. We show that, despite substantial decoherence due to thermal vibrations, nuclear energy loss, and, especially, excitations of the electronic system, FAD is not limited to insulator or semiconductor surfaces. Detailed studies of the geometric structure of insulator surfaces and superstructures on metal surfaces performed using FAD as an efficient virtually non-destructive method are presented.