Angular straggling in grazing scattering of fast He-atoms from an Al(111)-surface
Humboldt-Universität zu Berlin, Institut für Physik, Invalidenstrasse 110, 10115 Berlin, Germany
Accepted: 3 August 1998
We have studied the scattering of 2.3–8.0 keV neutral He-atoms from Al(111) under glancing angles of incidence ( to the surface plane). The polar angular distributions of scattered particles, measured in the plane defined by the incident beam direction and the surface normal, show a peak for specular reflection and exhibit small widths (about FWHM for incidence angle). Computer simulations reproduce the experiments in detail, showing that the angular straggling is caused by multiple scattering at 1) thermally displaced surface atoms, and 2) conduction electrons, where the latter mechanism seems to be dominant for small incidence angles. At high beam energies the observed angular straggling is larger than the simulated one, which may be due to fluctuations in the charge state of the projectiles and electronic excitations of the target.
PACS: 79.20.Rf – Atomic, molecular, and ion beam impact and interactions with surfaces / 61.85.+p – Channeling phenomena (blocking, energy loss, etc.) / 68.35.Bs – Surface structure and topography
© EDP Sciences, 1998