Do Hollow Atoms Exist in Front of an Insulating LiF(100) Surface?

Abstract

First measurements of $\mathrm{KLL}$ Auger spectra arising from collisions of ${\mathrm{N}}^{6+}$ ions on an insulating LiF(100) surface are presented. The beam energy is varied from 0.08 up to 16 keV. The incident angle is chosen such that the perpendicular velocity component is constant over the indicated energy range. Spectral features arising from above surface $\mathrm{KLL}$ emission, observed during interaction of ${\mathrm{N}}^{6+}$ with a conducting Si(100) surface, are absent for LiF, implying pronounced differences in the dynamics governing the above-surface neutralization and deexcitation of the highly charged projectiles.