title: Spectral diffusion in the tunneling spectra of ligand-stabilized undecagold clusters.
abstract: We report diffusion in the tunneling spectra of isolated, ligand-stabilized undecagold (Au11) clusters immobilized by attachment to alpha,omega-alkanedithiolate tethers inserted into alkanethiolate self-assembled monolayers. We use scanning tunneling microscopy and spectroscopy at cryogenic (UHV, 4 K) conditions to measure these clusters' conductance with complete control of their chemical and physical environment; additionally, thermal broadening of their electronic states as well as their mobility is minimized. At low temperature, the Au11 clusters demonstrate Coulomb blockade behavior, with zero-conductance gaps resulting from quantum size effects. Surprisingly, chemically identical and even single particles produced different families of tunneling spectra, comparable to previous results for heterogeneous distributions of particles. We hypothesize that, while these particles are chemically attached to the surface of the SAM for measurement, these assemblies may still be sufficiently dynamic to affect their transport properties significantly.
authors.affiliation: Departments of Chemistry and Physics, 104 Davey Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA.
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Smith
authors.forename: Sanjini U
authors.initials: SU
authors.lastname: Nanayakkara
authors.forename: Gerd H
authors.initials: GH
authors.lastname: Woehrle
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Pearl
authors.forename: Meaghan M
authors.initials: MM
authors.lastname: Blake
authors.forename: James E
authors.initials: JE
authors.lastname: Hutchison
authors.forename: Paul S
authors.initials: PS
authors.lastname: Weiss