Convoy electrons emitted by 2-MeV He+ ions at grazing incidence on KCl(0Â 0Â 1)

Convoy electrons produced during grazing angle scattering of 2-MeV He+ ions at a clean (0 0 1) surface of KCl are measured to see the effect of the surface track potential. The measurement is performed at 230 °C with a beam current far below 1 pA to avoid macroscopic charging. The observed convoy electron energy coincides with the energy of the electron isotachic to the incident ion. This suggests that the effect of the surface track potential is accidentally cancelled out by the surface wake potential.