Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Surface Chemical Reactions and Heterogeneous Catalysis III
O 49.4: Vortrag
Mittwoch, 2. April 2014, 11:15–11:30, PHY C 213
Functional Azobenzene based Self-Assembled Monolayers: molecular composition effects and photo switchable properties — •Swen Schuster1, Andreas Terfort2, and Michael Zharnikov1 — 1Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany — 2Institute for Inorganic und Analytical Chemistry, Frankfurt University, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
Control adjustment of work function of surfaces and interfaces by external stimuli is a challenging task. In this context, we designed novel photoresponsive, azobenzene-based self-assembled monolayers (SAMs) on gold and characterized them by synchrotron based high resolution x-ray photoelectron spectroscopy (HRXPS) and near-edge x-ray absorption fine structure spectroscopy (NEXAFS). The SAM precursors consisted of the thiol headgroup, a short aliphatic linker, azobenzene unit, and a functional tail group carrying a certain dipole moment. The length of the linker was varied to control the packing density in the monolayers, based on so called odd-even effect in monomolecular assembly. It was expected that the change in the orientation of the tail group upon the photoisomerization will result in a change of the work function of the entire system. The respective effects were monitored in situ by an ultra-high vacuum (UHV) Kelvin Probe. A clear signature of the photoisomerization behavior accompanied by the pronounced changes in the work function was found. The extent of the observed changes was related to the molecular structure (character of the tail group) and packing density in the SAM.