Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 4: Organische Dünnschichten I
O 4.6: Vortrag
Montag, 8. März 2004, 12:30–12:45, H43
Order and symmetries of sexithiophene within thin films studied by angle-resolved photoemission — •Cynthia Heiner1, Bernd Winter1, Jens Dreyer1, Hans-Hermann Ritze1, I.V. Hertel1, and Wolf Widdra2 — 1Max-Born-Institut, D-12489 Berlin — 2Universität Halle-Wittenberg, D-06099 Halle
We present angle-resolved photoemission (PE) spectra of ordered multilayer sexithiophene (6T) films, 2000 Å thickness, grown on a Au(110) single crystal. Structural order is crucial for film properties, particularly with regard to the performance of organic electronic devices. The measurements were performed at the MBI undulator beamline at BESSY, using photon energies < 100 eV. By simultaneous laser irradiation a compensation for film charging is achieved. The resulting spectra possess sharp features, which we show to have a strong intensity dependency on the experimental geometry. The molecules’ relative orientation, as interpreted through symmetry selection rules, is discussed in relation to various conformers. Our results firmly suggest the need for alternative molecular symmetries from the reported C2h symmetry for the 6T’s bulk-crystalline structure [1]. [1] R. N. Marks, M. Muccini, E. Lunedi, R. H. Michel, M. Murgia, R. Zamboni, C. Taliani, G. Horowitz, F. Garnier, M. Hopmeier, M. Oestreich, R. F. Mahrt, Chem. Phys. 227, 49 (1998).