Low-energy (10 to 500eV) He+ ions were scattered from the (001) surface and ejected electrons were detected. Two characteristic peaks were discerned in the electron energy spectra. One was attributed to the surface state of the (001) surface, resulting from Auger de-excitation of He*(3S) descended from He+. The other was due to auto-detachment of temporary He- ions. These two peaks broadened very little with increase in the velocity perpendicular to the surface, indicating that the electron emission occurred rather far from the surface. On the other hand, marked energy broadening depending upon the target species occurred if the electron was ejected via the Auger neutralization process. This was because Auger neutralization took place even in a close encounter with individual surface atoms.

Auger-Type Electron Emission from Energetic He+ Ions Interacting with the LaB6(001) Surface. Souda, R., Hayami, W., Aizawa, T., Otani, S., Ishizawa, Y.: Surface Science, 1996, 363[1-3], 133-8