EVIDENCE FOR THE SUPPRESSION OF INCIDENT BEAM EFFECTS IN AUGER-ELECTRON DIFFRACTION

Auger electron diffraction (AED) of the Cu(LOO) surface has been studi ed through the anisotropy of the elastic backdiffused beam electrons, the L2,3M4,5M4,5 (LVV) and the M2,3M4,5M4,5 (MVV) transitions in polar scan along the two main directions [001], [011] and in azimuth scan a t normal emission. The intensity anisotropies of the low and high kine tic energy Auger lines are in antiphase to each other as in experiment s in which these transitions are excited by X-ray photons. This behavi our has been exploited to single out the origin of the physical mechan isms accompanying the diffraction of the emitted electrons. Incident b eam effects appear to be sizeable only when the collection of the AED spectra an made with an angle integrating electron analyser (cylindric al mirror analyser or low electron energy diffraction apparatus), but they appear negligible when electron collection is performed through a small solid-angle detector. The conclusions reached by our measuremen ts are supported by good agreement with experimental and theoretical X -ray photoelectron diffraction data and demonstrate that, when the inc ident beam energy is sufficiently higher than the kinetic energy of th e Auger electron detected, the influence of the incident beam on AED i s negligible. (C) 1998 Elsevier Science B.V.