Precise total electron yield measurements for impact of singly or multiply charged ions on clean solid surfaces

Abstract

Total electron yields γ for impact of singly or multiply charged ions (H+, He+, He2+, N3+, N4+, O5+, O6+) on clean polycrystalline gold have been accurately measured at impact energies from almost zero [exclusive potential emission (PE) range] up to 40 keV times projectile charge state q (dominant kinetic emission range). Impact energies above 10 q keV have been approached by postacceleration of ions via target biasing with up to -30 kV. Total electron yields for γ≥3 have been derived directly from the related electron number statistics (ES) with total experimental errors of ±3%. Smaller values of γ have been determined from the related ES in conjunction with measurements of the respective primary ion, and ejected-electron currents, which caused somewhat larger experimental errors of typically ±5%. At higher impact velocity discrepancies arise between results from ES-based and current-based measurements of the total electron yield, respectively, because of systematic errors of the latter method due to projectile ion reflection and/or secondary ion emission from the target surface. For differently charged ion species, a difference in γ due to the q-related PE stays almost independent of the projectile impact energy. © 1997 American Institute of Physics.