Photoelectron spectroscopy of tin and lead cluster anions: application of halogen-doping method

Abstract

Abstract Electronic properties of tin (Sn) and lead (Pb) cluster anions were studied using photoelectron spectroscopy (PES) with a magnetic bottle-type electron spectrometer, where the feasibility of a halogen-doping method we recently developed was explored. The binary cluster anions containing a chlorine atom (Cl) were produced by a laser vaporization of a target rod in a He carrier gas mixed with a small amount of CCl 4 gas. Comparing the PES of Sn n Cl − and those of Sn n − , it was found that the doped Cl atom in Sn n Cl − deprives each Sn n − cluster of the excess electron without any serious rearrangement of the Sn n framework, which is similar to our previous work on Si n F − and Ge n F − . The halogen-doping method enables us to reveal the HOMO–LUMO gap of the corresponding neutral cluster of the Sn n clusters, showing that the Sn n clusters are semiconductor clusters, especially below n =30, similar to the Si n and the Ge n clusters. For the Pb n clusters, however, the halogen-doping method was inapplicable, which implies that the Pb n clusters are different from the other group-14 clusters, probably exhibiting a metallic nature.