Surface topography effects on energy-resolved polar angular distributions of ion-induced secondary electrons

From two models of surfaces modified by ion bombardment, polar angular distributions of electrons isotropically generated both inside and outside the crystal were calculated for different roughness parameters and various incidence angles. Under normal incidence, the angular distributions of electrons excited inside the solid follow a cosine law. For electrons generated outside the solid, but at a distance from the surface less than the depth of the surface depressions, the topographical modifications alter the expected constant polar angular distribution. A decreasing law was observed from a threshold value depending on the value of the roughness parameter. This preliminary work shows that previous results concerning polar angular distributions of Auger electrons belonging to the atomic-like lines observed in ion-induced Al L 23 Auger spectra have to be considered again taking into account the effect of surface texture.