Electron emission and ion reflection from Mg, Al and Si bombarded with 1–10 keV O + and Ne + at impact angles between 0° and 84°

Abstract

The total electron yields produced by bombarding Mg, Al and Si with low-velocity O + and Ne + ions have been measured at angles of incidence between normal and glancing. The yields were found to increase with increasing angle, but less pronounced the lower the ion velocity. The results suggest that the electron yields become independent of the impact angle as the ion velocity approaches the threshold for kinetic electron emission. This novel feature may be related to pronounced angular straggling of the injected ions and/or to significant ion stopping within the electron escape depth. With decreasing ion velocity the maxima of the angular dependent electron yields shift from above 84° to about 75°. Reflection of primary ions can disturb the electron yield measurements, more so the larger the impact angle. A large fraction of the reflected projectiles appears to be in an ionized state, notably in the case of neon.