Above-surface neutralization of slowN6+ions during interactions with a Cu(001) target

Measurements are reported for projectile K-Auger-electron emission, observed at 90° to the incident beam direction, during interactions of 60-keV ${\mathrm{N}}^{6+}$ ions with a clean Cu(001) target at grazing incidence angles in the range 0.2°–20°. Spectral features in the projectile K-Auger-electron spectra consistent with above-surface K-Auger-electron emission were observed at perpendicular velocities below 1.37×${10}^{\mathrm{-}2}$ a.u. (incidence angle Ψ<1.9°). At incidence angles below 0.8° (${\mathit{v}}_{\mathrm{\perp }}$<5.8×${10}^{\mathrm{-}3}$ a.u.) the above-surface K Auger yields were observed to saturate, reaching a maximum value of about 12% of the total K-Auger-electron production. The present results are in good agreement with earlier measurements.