NON LINEAR EFFECTS IN ION INDUCED ELECTRON EMISSION

High-resolution zero-degree electron spectra, total electron yields as well as Auger-electron spectra have been taken for 5 MeV/u ions (N 7+ , S 13+ , Ni 23+ , and Ag 37+ ) penetrating carbon and insulator foils at normal incidence. A shift of the convoy-electron velocity with respect to the experimentally determined projectile velocity is found. For the carbon target, there is an acceleration of convoy electrons, whereas for the insulating targets, there is a deceleration of convoy-electrons as well as a deceleration of target-Auger electrons. These experimental findings are compared to theoretical estimates for dynamic ion-induced potentials.