Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 49: Particles and Clusters

O 49.7: Talk

Wednesday, February 27, 2008, 16:45–17:00, MA 005

Ag cluster growth on biaxially oriented PET — •Günther Weidlinger, Lidong Sun, José Manuel Flores-Camacho, Michael Hohage, Daniel Primetzhofer, Peter Bauer, and Peter Zeppenfeld — Institut für Experimentalphysik, Johannes Kepler Universität Linz, Altenberger Straße 69, A-4040 Linz

Ag was deposited on biaxially oriented polyethylene terephthalate (PET) by means of Physical Vapor Deposition under UHV conditions up to a nominal Ag layer thickness of 5 nm. Since Ag does not wet the PET surface, Ag clusters are formed on the surface rather than a continous metal film. The optical properties of these silver clusters were monitored with Reflectance Difference Spectroscopy (RDS) during metal deposition. Morphological studies of the samples reveal that the clusters are embedded in the PET substrate and that the shape of the individual clusters as well as their in-plane arrangement is isotropic. Despite the structural isotropy of the Ag clusters, an in-plane anisotropy of the cluster plasmon resonance can be observed in the RD spectra. This is attributed to the anisotropic dielectric properties of the substrate and its influence on the plasmon response. At low nominal Ag thicknesses (≤0.3 nm), the FWHM and the energy position of the plasmon resonance show a 1/R-dependence on the cluster radius R. A broadening and an accelerated red-shift of the resonance due to retardation effects and cluster-cluster interactions are observed for silver thicknesses above 0.3 nm.