title: Optical absorption spectrum of gold atoms deposited on SiO(2) from cavity ringdown spectroscopy.
abstract: The optical properties of gold atoms supported on amorphous silica (alpha-SiO2) were studied experimentally and theoretically in the visible range. Samples were prepared in situ by depositing Au atoms at low coverages (5 x 10(12) cm(-2)) in UHV, and the optical absorption spectra were recorded by cavity ringdown spectroscopy. The atomic absorption bands can be attributed to gold atoms trapped at [triple bond] Si-O(.-) and [triple bond]Si-O(-) defect sites. The absence of optical transitions typical for Au(2) shows that the atoms are efficiently anchored at these defect sites, preventing diffusion and aggregation. Furthermore, these experimental results reveal that it is now possible to study optical properties of well-defined nanostructures at surface coverages as low as 5 x 10(11) cm(-2).
authors.affiliation: Lehrstuhl für Physikalische Chemie 1, Technische Universität München, D-85747 Garching, Germany. jean-marie.antonietti@chemie.uni-ulm.de
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Antonietti
authors.forename: Marcin
authors.initials: M
authors.lastname: Michalski
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heiz
authors.forename: Harold
authors.initials: H
authors.lastname: Jones
authors.forename: Kok Hwa
authors.initials: KH
authors.lastname: Lim
authors.forename: Notker
authors.initials: N
authors.lastname: Rösch
authors.forename: Annalisa Del
authors.initials: AD
authors.lastname: Vitto
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Pacchioni