PNNL

Abstract

The electronic structure of Snn - clusters _n=4–45_ was examined using photoelectron spectroscopy at photon energies of 6.424 eV _193 nm_ and 4.661 eV _266 nm_ to probe the semiconductor-to-metal transition. Well resolved photoelectron spectra were obtained for small Snn -clusters _n_25_, whereas more congested spectra were observed with increasing cluster size. A distinct energy gap was observed in the photoelectron spectra of Snn - clusters with n_41, suggesting the semiconductor nature of small neutral tin clusters. For Snn - clusters with n_42, the photoelectron spectra became continuous and no well-defined energy gap was observed, indicating the onset of metallic behavior for the large Snn clusters. The photoelectron spectra thus revealed a distinct semiconductor-to-metal transition for Snn clusters at n=42.