Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 9: Organic films I
O 9.2: Vortrag
Montag, 27. März 2006, 15:15–15:30, TRE Phys
Comparison of gas– and condensed phase NEXAFS spectra of large organic molecules — •Florian Holch1, Dominique Hübner1, Achim Schöll1, Rainer Fink2, and Eberhard Umbach1 — 1Universität Würzburg, Experimentelle Physik II — 2Universität Erlangen, Physikalische Chemie II
The interaction
between most large organic molecules in the solid state is commonly
believed to be solely due to electrostatic and van–der–Waals
forces. An analysis of these intermolecular effects requires a
comparison of high–quality spectroscopic data of gaseous and
condensed organic molecules. In this work we present
high–resolution NEXAFS spectra of
1,4,5,8–naphthalene–tetracarboxylic acid dianhydride (NTCDA) and
acenaphthenequinone (ANQ) in the gas phase and solid state. For the
gas phase experiments a new experimental set–up has been used that
allows the measurement of substances with high sublimation
temperatures. A detailed Franck–Condon analysis of the
vibronic fine structure of the NTCDA spectra at the C K–edge
yields consistent results for both phases. In contrast, pronounced
differences in the electronic features between gas phase and
condensate can be demonstrated. This corroborates the results for
ANQ that also suggest an involvement of the π∗–orbitals of
the aromatic core in the intermolecular interaction. Our findings
thus indicate that intermolecular forces can be much stronger than
commonly believed and may even cause the formation of
intermolecular bonds.
The project is financed by the BMBF under contract 05KS4WWC/2