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O: Oberflächenphysik
O 5: Zeitaufgelöste Spektroskopie I
O 5.6: Vortrag
Freitag, 4. März 2005, 12:00–12:15, TU EB107
Ultrafast electron dynamics in C6F6/Cu(111) analyzed with time-reslved photoelectron and resonant Auger-Raman spectroscopy — •P. Kirchmann1, P. Loukakos1, U. Bovensiepen1, M. Wolf1, V. Sethuraman2, A. Pietsch2, F. Hennies2, M. Nagasono2, A. Föhlisch2 und W. Wurth2 — 1Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin — 2Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg
Ultrafast charge transfer processes in molecules adsorbed on a metal surface can be investigated by resonant Auger-Raman spectroscopy [1] and femtosecond time-resolved two-photon-photoemission (2PPE) [2]. To systematically compare both techniques we investigated the system C6F6/Cu(111). This study reveals a qualitatively different coverage dependence of the decay rate of the lowest unoccupied molecular resonance. In addition the decay rate for monolayer coverages measured by the two methods is different by a factor of five. This is attributed to the fact that Auger-Raman spectroscopy detects intra-molecular charge delocalization as well as the delocalization between the molecule and its environment. In contrast, 2PPE probes the intraband scattering within delocalized states of the molecular adlayer as well as the population decay by interband scattering to the substrate. Thus different relaxation channels are measured with the two approaches. The project was funded by the DFG through SPP 1093.
[1] W.Wurth and D.Menzel, Chem. Phys. 251, 141 (2000)
[2] C.Gahl, K. Ishioka, Q. Zhong, A. Hotzel and M. Wolf, Faraday. Discuss. 117, 191 (2000)