Deviations from the coulomb staircase in scanning tunneling microscopy experiments of nanometer-sized metal clusters

摘要

In this paper we describe two types of deviations from the regular Coulomb staircase that have been observed in tunneling spectroscopy on single isolated metal clusters. The first type of deviation is observed above granular films and consists of jumps of the tunnel characteristics in time. This effect is explained by trapping and detrapping of charge in the oxide between the cluster and the substrate. the second type of deviations has been observed on ligand stabilized metal clusters and consisted of additional steps on the Coulomb staircase. These additional steps can be explained by quantum levels in the cluster.