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O: Fachverband Oberflächenphysik

O 59: Plasmonics and Nanooptics

O 59.21: Poster

Tuesday, March 21, 2017, 18:30–20:30, P2-OG1

Plasmon dispersion and dielectric funtion at a silver/porphyrin interface — •Klaus Stallberg and Winfried Daum — Institute of Energy Research and Physical Technologies, TU Clausthal, Leibnizstraße 4, 38678 Clausthal-Zellerfeld, Germany

Multi-photon photoelectron microscopy (nP-PEEM) is a valuable tool for the investigation of propagating surface plasmon polaritons (SPP). It has been demonstrated by other groups that nP-PEEM allows for a determination of the complex SPP wavevector. In our contribution we adapt this method to determine the SPP dispersion curve on a microscopic Ag(111) island. Our results are in good agreement with results from the literature which were obtained with all-optical methods on extended silver films. We further investigate the SPP dispersion at a silver/zinc-tetraphenylporphyrin interface, which can be regarded as a model system for SPP propagation in the presence of a dielectric with a strong optical absorption band. For excitation wavelengths near the porphyrin absorption (Soret-) band, the shape of the SPP dispersion curve signals an interaction of molecular and plasmonic excitations. In addition, we demonstrate that with nP-PEEM the complex dielectric constant of a thin organic film can be determined as a function of the film thickness during growth. Moreover, we investigate the frequency dispersion of the complex dielectric function of the porphyrin film.