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O: Fachverband Oberflächenphysik
O 60: Time-Resolved Spectroscopies
O 60.3: Vortrag
Donnerstag, 29. März 2007, 16:15–16:30, H42
Femtosecond electron dynamics in atomic wires: Si(557)-Au — •Tilman K. Rügheimer1,2, Franz Himpsel2, and Thomas Fauster1 — 1Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen — 2Department of Physics, University of Wisconsin-Madison, 1150 University Ave, Madison WI 53706, USA
Atomic wires of noble metals such as gold on silicon surfaces serve as a model system for the investigation of one-dimensional electron systems. Recent experiments on Si(557)-Au have proven the existence of a spin-split surface state band below EF [1] and have provided first information on the unoccupied part of the electronic band structure [2,3]. The dynamics of electrons has not been investigated so far.
We have carried out time-resolved two-photon photoemission experiments using femtosecond laser pulses. The lifetime of the previously reported image-potential resonance [2] is found to be smaller than 10 fs. At energies in the bulk band gap, the I ( Δ t ) curves are strongly asymmetric and cannot be explained by a single state and one decay channel. An interpretation using electron scattering between surface states in the gap is used to fit the data and reveals several lifetimes on the femtosecond and the picosecond scale.
[1] I. Barke et al., Phys. Rev. Lett. 97, 226405 (2006)
[2] J. A. Lipton-Duffin et al., Phys. Rev. B 73, 245418 (2006)
[3] T. K. Rügheimer et al., submitted