Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 27: Time-Resolved Spectroscopy II
O 27.1: Talk
Tuesday, February 26, 2008, 11:15–11:30, MA 043
Unoccupied band-structure and hot electron lifetimes in Pb and Bi quantum-wells — Andreas Ruffing1, •Stefan Mathias1, Martin Wiesenmayer2, Luis Miaja-Avila3, Frederik Deicke1, Henry Kapteyn3, Margaret Murnane3, and Michael Bauer2 — 1Department of Physics, TU Kaiserslautern, 67663 Kaiserslautern — 2Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Germany — 3JILA, University of Colorado, Colorado 80309-0440, USA
The two-dimensional electronic structure of metallic quantum wells (QW) enable an unique access to peculiarities of solid state band structures by means of momentum resolved photoelectron spectroscopy, such as avoided crossings, band gaps or modifications due to interactions at interfaces. With respect to ultrafast dynamical processes in metals these features are highly interesting as they enable for instance insights into the relevance of band-structure details for the decay of hot electrons. Momentum and time-resolved two-photon photoemission (2PPE) performed with a two-dimensional electron analyzer for parallel energy (E) and momentum (k||) detection provide the required sensitivity for such experiments. In this contribution we will present and discuss first results obtained for ultrathin Pb and Bi quantum wells grown on a Cu(111) substrate. The 2PPE experiments enable us to directly map the unoccupied band structure of these systems and the according momentum resolved hot electron lifetime τ(E,k||).