Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 16: Organic, polymeric, biomolecular films - also with adsorbates

O 16.2: Vortrag

Montag, 22. März 2010, 15:15–15:30, H46

Photoisomerization of azobenzene on layer compound surfaces studied by photoelectron spectroscopy — •Eric Ludwig¹, Jaroslaw Iwicki¹, Kai Rossnagel¹, Felix Köhler², Rainer Herges², and Lutz Kipp¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Kiel, D-24098 Kiel, Germany — ²Otto-Diels-Institut für Organische Chemie, Universität Kiel, D-24098 Kiel, Germany

Photoswitchable azobenzene and its derivative Disperse Orange 3 (DO3) molecules were deposited in situ under UHV conditions on the surfaces of the metallic and semiconducting layered crystals TiTe₂ and HfS₂, respectively. Due to weak van der Waals-like coupling between the layers these materials serve as excellent substrates for the analysis of adsorbed molecules and their possible photoswitching behavior. Coverages from sub-monolayer to several monolayers were realized. Photoelectron spectroscopy (PES) experiments were performed using a He discharge lamp and a SPECS Phoibos 150 analyzer. Results imply Stranski-Krastanov-like film growth of azobenzene on TiTe₂. Comparison of PES spectra to outer valence green function calculations suggests dimer formation of DO3. To photoisomerize the adsorbed molecules, the samples were irradiated with a LED Power Pen (wavelength 365 nm, 3.5 W/cm²). Experimental data of azobenzene adsorbed on HfS₂ shows that the molecules can be partially switched from the trans to the cis orientation. On TiTe₂ no switching has been observed, presumably due to stronger molecule-substrate coupling. This work was supported by the DFG through SFB 677.