Hamburg 2001 – wissenschaftliches Programm
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SYOF: Organische Festkörper
SYOF 5: Poster Session
SYOF 5.29: Poster
Dienstag, 27. März 2001, 17:00–19:00, Aula S3
Optical Spectroscopy on ultrathin epitaxial organic films: PTCDA/Ag(111) — •M. Schneider1, C. Bauer2, 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-, Ramanspectroscopy and LEED. The
optical spectra show a strong dependency on the preparation
conditions, especially the substrate temperature during the
growth process and the film thickness. The vibrational modes
observed with polarisation dependent Raman spectroscopy are
compared with theoretical calculations and can be assigned in
detail. The Raman spectroscopy of the mono- and bi-layers is of
special interest, because these ultrathin films are not
accessible by conventional PL- or PLE- experiments due to a very
effective quenching of the luminescence on the metal substrate.
The influence of the substrate leads to strong differences in the
Raman spectra of the first two layers compared to the spectra of
the multilayer films. From the results of our experiments we draw
conclusions on the effect of the strong binding on the metal
surface on the vibrational properties of the molecules.
Supported by DFG Um 6/4-2.