title: Chemically induced metal-to-insulator transition in Au55 clusters: effect of stabilizing ligands on the electronic properties of nanoparticles.
abstract: The cluster compound Au55(PPh3)12Cl6 has been reanalyzed by photoelectron spectroscopy giving direct evidence for a nonmetallic behavior of the individual Au clusters as long as their ligand shell remains intact. The exposure to x-rays during the measurements is found to partly decompose the shell by removal of the chlorine atoms, resulting in a metallic behavior of the clusters as demonstrated by a steplike intensity at the Fermi energy. These observations resolve a long-standing controversy about the metallic behavior of ligated Au clusters emphasizing, in addition, the influence of the local environment on the electronic properties of nanoscaled materials.
authors.affiliation: Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm, Germany. hans-gerd.boyen@physik.uni-ulm.de
authors.forename: H G
authors.initials: HG
authors.lastname: Boyen
authors.forename: G
authors.initials: G
authors.lastname: Kästle
authors.forename: F
authors.initials: F
authors.lastname: Weigl
authors.forename: P
authors.initials: P
authors.lastname: Ziemann
authors.forename: G
authors.initials: G
authors.lastname: Schmid
authors.forename: M G
authors.initials: MG
authors.lastname: Garnier
authors.forename: P
authors.initials: P
authors.lastname: Oelhafen