Evolution of KLL-Auger decay from N 6+ → Au(111) above the first layer

Abstract

Auger electrons originating in the interaction of N 6+ ions with a Au(111) surface are measured. Solid-state effects acting on the ions as well as on the electrons are clearly detected although the experimental conditions guarantee emission only from above the top layer of target atoms. KLL electrons emitted from neutralized projectile states with low ( n L = 2, i.e. hollow atom) and high ( n L = 5, 6) L-shell population can be distinguished. It is shown by Doppler shift analysis of the electron energies that the emission from hollow atom states occurs after the image acceleration of the projectile but before it is reflected by the surface, and the emission with filled L-shell after the reflection. The angular distributions for both electron groups are different and depend on the ion energy. This is explained in terms of different height z at emission, by the effect of electron refraction by the z-dependent surface potential barrier.