Regensburg 2004 – wissenschaftliches Programm
O 33.4: Vortrag
Donnerstag, 11. März 2004, 12:00–12:15, H39
Electron-vibron coupling in the NEXAFS spectra of large organic molecules — •Dominique Hübner1, A. Schöll1, R. Fink2, K.C. Prince3, R. Richter3, S. Stranges4, and E. Umbach1 — 1Univ. Würzburg, Exp. Phys. II — 2Univ. Erlangen, Phys. Chem. II — 3Sincrotrone Trieste — 4CNR-Istituto di Metodologie Inorganiche e dei Plasmi
High-resolution NEXAFS spectroscopy is ideally suited to investigate the electronic structure of large organic molecules in both, the condensed and the gas phase. In ideal cases one observes distinct fine structures which are attributed to the electron vibron coupling. Astonishingly, the electronic excitations significantly couple to few vibronic states. We present NEXAFS data on the heteroaromatic molecule acenaphthenequinone (ANQ). ANQ is at present the largest molecule for which vibronic fine structure has been observed for O K-edge excitations. Remarkably, the O K-edge spectra of the condensed and gas phase hardly differ. The well-resolved data furthermore allow to describe the anharmonicity of the excited state potential. Whereas there are no differences for O 1s excitations, the comparison for the C K-edge for the condensed and gas phase gives clear hints that the π-interactions between neighboring molecules mostly involves the aromatic core. The project is financed by BMBF under contract 05 KS1 WWA/5.