Chemically induced metal-to-insulator transition in Au55 clusters: effect of stabilizing ligands on the electronic properties of nanoparticles.
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.
Boyen
H G
HG
Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm, Germany. hans-gerd.boyen@physik.uni-ulm.de
Kästle
G
G
Weigl
F
F
Ziemann
P
P
Schmid
G
G
Garnier
M G
MG
Oelhafen
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P