Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)
O 36.70: Poster
Montag, 7. März 2005, 15:00–18:00, Poster TU F
Two-photon-photoemission spectroscopy of supported silver clusters — •Mihai E. Vaida1, Tobias Gleitsmann1, Bert Stegemann2, Thorsten M. Bernhardt1, and Ludger Wöste1 — 1Freie Universität Berlin, FB Physik, Arnimallee 14, D-14195 Berlin, Germany — 2Bundesanstalt für Materialforschung und -prüfung, BAM VIII.1 Tribologie und Verschleißschutz, Unter den Eichen 44-46, D-12205 Berlin, Germany
In order to get an insight into the electronic properties of atomic silver clusters, we set up the technique of time-resolved two-photon-photoemission spectroscopy (2PPS) to a well-defined cluster-support system consisting of silver clusters on an atomically flat insulating thin film of magnesia. The goal is to determine the electronic level structure of the supported silver clusters as a function of cluster size as well as the corresponding excited state lifetimes to identify possible radiative and non-radiative transitions. For this purpose we set up a new experimental arrangement combining a high intensity continuous sputter clusters source (CORDIS) with an UHV-chamber for surface analysis. The cluster ions are mass-selected via quadrupole mass-filter, thermalized, deflected out of the beam production line and subsequently guided by electrostatic lenses and an octopole ion guide onto a MgO/Mo(100) surface. The 2PPS experiments will be carried out by utilizing a home-built field free time-of-flight electron spectrometer. The light source consists of an amplified kHz femtosecond laser system and an optical setup for pump-probe measurements with a typical pulse length of about 40 fs.