Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 2: Electronic Spectroscopy

MO 2.4: Vortrag

Montag, 12. März 2012, 11:15–11:30, V38.02

Photoionization of hydroxy-substituted [2.2]paracyclophanes with VUV synchrotron radiation — •Patrick Hemberger¹, Christof Schon², Andras Bodi¹, Michael Steinbauer², Kathrin H. Fischer², and Ingo Fischer² — ¹Paul Scherrer Institute, Molecular Dynamics Group, CH-5232 Villigen PSI — ²Institute of Physical and Theoretical Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg

π-conjugated molecules are widely applied in optoelectronic devices such as organic light emitting diodes. Paracyclophanes are possible new candidates to expand the variety of these materials because of their interesting physical properties, like the coupling between the two benzene rings. The photoionization and dissociative photoionization of hydroxy-substituted [2.2]paracyclophanes were investigated at the VUV beamline of the Swiss Light Source, especially the substituent effects on the ionization energies when the benzene frameworks are hydroxy-substituted. At a photon energy of around 10 eV, the sample starts to dissociatively photoionize. The most prominent channel is the dissociation of both C-C bonds of the CH₂-CH₂ bridges in para position between the two phenol rings leading to the molecule fragmenting in half. The data were subsequently modeled in order to obtain appearance energies, which then lead to bond dissociation energies and other thermochemical data. In addition calculations were performed, which reveal that even DFT functionals, which take into account dispersion interactions (ω-B97XD), fail to predict the appearance energies correctly.