Ion beam induced formation and interrogation of Au nanoclusters

Low-energy ion bombardment of a Au thin film by 0.5 keV Ar+ forms self-organized nanoclusters that display quantum size effects. The reduction of Au coverage with sputtering time is quantified with x-ray photoemission spectroscopy, and a decrease of both the rms roughness and correlation length is measured by STM. Neutralization of scattered 3 keV Na+ and K+ alkali-metal ions is used to probe the electronic states of the sputter-induced nanoclusters. The neutral fractions gradually increase as the cluster dimensions decrease, indicating that the electronic structure is similar to that of clusters grown by deposition.