Electronic shells and supershells in trivalent metal clusters

Abstract

Electronic shell structures are observed for the first time in large gallium and aluminum clusters. In gallium, the electronic shells extend up to 7000 electrons and a nice supershell structure is obtained around 2500 electrons. This number is considerably larger than expected from standard jellium calculations and is consistent with the introduction of a small surface softness. In aluminum, the clusters are more rigid and in usual experimental conditions they have specific geometric arrangement. However by heating the source nozzle, we obtain liquid-like aluminum clusters and observe the electronic shell structure up to 1800 electrons.