Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 43: Time-resolved spectroscopy I
O 43.3: Vortrag
Donnerstag, 30. März 2006, 18:00–18:15, WIL C207
Time-Resolved Two-Photon Photoemission study of C60 — •Arne Rosenfeldt, Benjamin Göhler, and Helmut Zacharias — University of Münster, 48149 Münster, Germany
Up to 200 ML of C60 on Cu(111) are illuminated by tunable 365 to 415 nm (3.40 to 2.99 eV) radiation of 50 ps pulse duration. Delayed 263 nm (4.71 eV) photons have sufficient energy to probe half of the LUMO and the LUMO+1. A rate equation fitted to the electron dynamics suggests a short lifetime of about 126 ps for the LUMO, and another one longer than 5 ns, which may originate from excitons with the same energy as the LUMO. The excitation probability of these states is measured as a function of photon energy, showing a maximum at 392 nm (3.16 eV). Using four-wave mixing in Xenon radiation at 150 nm (8.27 eV) is generated to investigate low-lying states. For measurement of long lifetimes a second laser is electronically delayed. The project is financially supported by the DFG in the SPP1093 “Dynamik von Elektronentransferprozessen an Grenzflächen”