Structural and bonding properties of ScSi_n^- (n=2～6) clusters: photoelectron spectroscopy and density functional calculations

Anion ion photoelectron spectroscopy and density functional theory (DFT) are used to investigate the electronic and structural properties of ScSi_n^ - (n=2\sim6) clusters and their neutrals. We find that the structures of ScSi_n^ - are similar to those of Si_n + 1^ - . The most stable isomers of ScSi_n^ - cluster anions and their neutrals are similar for n=2, 3 and 5 but different for n=4 and 6, indicating that the charge effect on geometry is size dependent for small scandium--silicon clusters. The low electron binding energy (EBE) tails observed in the spectra of ScSi_4,6^ - can be explained by the existence of less stable isomers. A comparison between ScSi_n^ - and VSi_n^ - clusters shows the effects of metal size and electron configuration on cluster geometries.