Regensburg 2004 – wissenschaftliches Programm
O 10.5: Vortrag
Montag, 8. März 2004, 16:45–17:00, H43
Photon Emission Spectroscopy on Individual Oxide-Supported Ag-Au Alloy Clusters — •W. Benten, N. Nilius, N. Ernst, and H.-J. Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin
Intermixing of different metals to small bimetallic particles causes distinct changes in physical and chemical properties. Since plasmon-induced light emission is sensitive to the composition of the alloy particles, optical emission spectroscopy can be used to determine details of the alloying process. We have combined photon emission spectroscopy with scanning tunnelling microscopy to analyse optical properties of individual Ag-Au clusters deposited on a thin Al2O3 film on a NiAl (110) substrate. For pure Ag and Au clusters, we measured well-defined photon emission peaks at around 320 nm and 510 nm, respectively, attributed to Mie-plasmon excitations. After mixing of both materials, intermediate photon emission peaks are observed indicating the formation of alloy clusters on the surface. Peak positions and widths are examined for different composition and compared with theoretical predictions based on Mie-theory.