Three-electron Auger processes observed in collisions of bare ions on a metal surface

The electron spectra arising from collisions of bare ions (C6+ and N7+) on a clean Ni(110) surface show a small but distinct peak at about twice the normal Auger energy, which we ascribe to three-electron K2L2L Auger processes. The intensity of these three-electron Auger transitions indicates a strong filling of the L-shell prior to the decay of the inner shell vacancies.