Regensburg 2002 – wissenschaftliches Programm
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SYOH: Organische Halbleiter
SYOH 7: Poster
SYOH 7.5: Poster
Montag, 11. März 2002, 18:00–21:00, C
Optical Spectroscopy on ultrathin epitaxial organic films: PTCDA/Ag(111) — •M. Schneider1, T. Muck2, C. Bauer2, L. Chkoda1, V. Wagner2, J. Geurts2, M. Sokolowski3, and E. Umbach1 — 1Experimentelle Physik II — 2Experimentelle Physik III, Univ. Würzburg, Am Hubland, 97074 Würzburg — 3Institut für Physikalische und Theoretische Chemie, Univ. Bonn, Wegelerstr. 12, 53115 Bonn
We report about our experiments on the optical properties of
ultrathin epitaxial films of PTCDA on the highly ordered
substrate Ag(111). The films were prepared under UHV-conditions
and characterized by PL, PLE, Raman spectroscopy, AFM and LEED. The
optical spectra show a strong dependency on the preparation
conditions, especially the substrate temperature during the
growth process and some observations can be explained with the exciton
band structure [1].
In polarisation dependend Raman spectroscopy some of the vibrational
modes
show a Davydov-splitting which is also dependend on the preparation
conditions. Theoretical
calculations for the known structures of the single crystals with
van-der-Waals interacting
molecules give (for this simple model) astonishing good agreements with
the measured
Davydov-splitting. The results of the optical measurements and the
calculations are discussed
and compared to the morphology and structure of the films.
(Supported by DFG Um 6/4-2).
[1] M. Hoffmann et al. Chem. Phys. 258 (2000)