Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 79: Plasmonics and Nanooptics IV

O 79.10: Talk

Thursday, April 3, 2014, 18:15–18:30, TRE Ma

Multi-photon photoelectron microscopy of porphyrin thin films in contact with plasmonic silver structures — •Klaus Stallberg and Winfried Daum — Intstitute of Energy Research and Physical Technologies, TU Clausthal, Leibnizstraße 4, 38678 Clausthal-Zellerfeld

Porphyrins represent a prominent class of molecules with extended π-electron system extensively studied for light harvesting and solar energy conversion. Recent studies showed strong coupling of molecular excitations in J-aggregates of porphyrins with surface plasmons of metallic films and plasmonic nanostructures. We study the interaction of magnesium-tetraphenylporphyrin (Mg:TPP) excited states (S₂ level, Soret band) with localized surface plasmons (LSPs) in silver nanostructures by energy-resolved photoemission electron microscopy (PEEM) and by photoelectron excitation with short laser pulses for time-resolved single particle spectroscopy. As a first step in this direction we fabricated silver nanoparticles with a broad distribution of sizes and LSP resonances by evaporation of silver through a mask of polysterene spheres onto a natively oxidized silicon substrate. By variation of the photon excitation wavelength we identify LSP resonances that match the Mg:TPP Soret band. We also report on wavelength-dependent PEEM experiments with Mg:TPP films deposited on substrates with more homogeneous Ag nanoparticles prepared from solutions. First results from time-resolved 2- and 3-photon photoemission pump-probe experiments on Mg:TPP films are presented.