Date of this Version
A variety of experimental techniques are used to resolve energetically close isomers of Au7 − and Au8 − by combining photoelectron spectroscopy and ab initio calculations. Two structurally distinct isomers are confirmed to exist in the cluster beam for both clusters. Populations of the different isomers in the cluster beam are tuned using Ar-tagging, O2-titration, and isoelectronic atom substitution by Cu and Ag. A new isomer structure is found for Au7 −, which consists of a triangular Au6 unit with a dangling Au atom. Isomer-specific photoelectron spectra of Au8 − are obtained from O2-titration experiment. The global minimum and low-lying structures of Au7 −, Au8 −, and MAun − (n=6,7; M=Ag,Cu) are obtained through basin-hopping global minimum searches. The results demonstrate that the combination of well-designed photoelectron spectroscopy experiments (including Ar-tagging, O2-titration, and isoelectronic substitution) and ab initio calculation is not only powerful for obtaining the electronic and atomic structures of size-selected clusters, but also valuable in resolving structurally and energetically close isomers of nanoclusters.