Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 45: Organic-Inorganic Hybrid Systems and Organic Films

O 45.22: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1A

Polarization-Dependent Excitation of Porphyrin Nanostructures investigated by PEEM — Hannes Hartmann, Karl-Heinz Meiwes-Broer, •Ingo Barke, and Sylvia Speller — University of Rostock, Institute of Physics, 18059 Rostock

In photoemission the dependence on light polarization can help to access the internal structure of molecule aggregates. Recently we selectively mapped excited states in copper tetraundecylporphyrin (CuTUP) nanostructures on graphite (HOPG) using two-photon photoemission electron microscopy (2PPE-PEEM) [1]. Here we present polarization-dependent and spatially resolved electron yields of the same system using varying excitation wavelengths. We observe a Davydov-like splitting of the Soret band which shows a systematic dependence on the specific location. By varying the light polarization this spatial effect is correlated with the direction of the transition dipole moments. These results are discussed in view of orientation and internal structure of the CuTUP assemblies. In addition we observe characteristic variations of the photoelectron intensity which is found to be connected to the local height as determined by correlative atomic force microscopy measurements. This behavior is analyzed in the framework of vertical optical standing waves within the CuTUP structures.

[1] H. Hartmann et al., J. Phys. Chem. C 120, 16977 (2016)