Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.79: Poster
Tuesday, March 27, 2012, 18:15–21:45, Poster B
Electronic states on Si(111)-(5×2)-Au — •Kerstin Biedermann and Thomas Fauster — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany
Submonolayers of gold on vicinal Si(111) surfaces form a variety of atomic chain structures and hence serve as a model system for one-dimensional electronic systems. We concentrate here on the Si(111)-(5×2)-Au surface, which exhibits three gold chains per unit cell.
Angle- and time-resolved two-photon photoemission experiments were carried out using infrared (IR, EIR=1.55 eV) and ultraviolet (UV, EUV=4.65 eV) femtosecond laser pulses. For photoemission (UPS) experiments the fourth harmonic (IR+UV) provided a source of 6.2 eV photons. The polarization of all beams could be chosen independently. Using optical dipole-selection rules, at normal emission, we evaluated the parity of the electronic states, which is either even or odd with respect to the (110) mirror plane orthogonal to the gold chains.
Apart from bulk transitions we observed an even, short-lived (τ<20 fs) n=1 image-potential resonance and a long lived feature (τ>600 fs) within the bulk band gap of silicon. States related to the gold chains were detected at high emission angles. We present here an analysis of our time-, angle- and energy-resolved measurements and compare our findings to the Si(557)-Au and Si(553)-Au surfaces.