Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Metal substrates: Adsorption of organic / bio molecules I
O 4.4: Vortrag
Montag, 23. März 2009, 12:00–12:15, SCH A118
Electronic Structure of the Hexaketo- and Hexamethoxy- Substituted Coronene Nanographenes on Au — •Medjanik K.1, Naghavi S.2, Rieger R.3, Kutnyakhov D.1, Nepijko S.A.1, Schönhense G.1, Alijani V.2, Felser C.2, Baumgarten M.3, and Muellen K.3 — 1Institut für Physik, Universität Mainz — 2Institute for Analytic and Anorganic Chemistry Univ. Mainz — 3Max-Planck-Institute for Polymer Research, Mainz
The electronic structure of the donor hexamethoxycoronene and the acceptor coronene-hexaone adsorbed on gold surfaces has been studied by UPS. There substituted nanographenes are synthesized by a novel route described in [1]. A special evaporation system has been developed that is suitable for milligram amounts of evaporant materials. The electronic structure of the keto- and methoxy-species is substantially different because the ligands strongly influence the aromatic system. The keto-species exhibits a significant energetic level shift in the first monolayer with the HOMO being shifted by 1.5 eV towards lower binding energies. The transition from monolayer to multilayer is accompanied by a characteristic variation of the work function that exhibits a sharp minimum. The methoxy species, in contrast, shows constant peak positions throughout the coverage range (along with a continuous drop of the work function) but already for thin layers strong charging sets in. An ab-initio calculation (Gaussian03) has been performed that shows good agreement.
Funded by DFG through Transregio SFB TRR 49
[1] R. Rieger et al., Chem. Eur. J. 14 (2008) 6322