Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 72: Symposium: Beyond Optical Wavelengths: Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation II (Invited Speakers: Wilfried Wurth, Hermann Dürr, Shik Shin)
O 72.8: Vortrag
Donnerstag, 28. Februar 2008, 16:45–17:00, HE 101
Ultrafast charge transfer at silicon surfaces investigated by the core hole clock method: Band structure influences — Silvano Lizzit1, Guillermo Zampieri1,2, Luca Petaccia1, Rosanna Larciprete1,3, Krassimir L. Kostov4, Georgi Tyuliev5, and •Dietrich Menzel6,7 — 1Sincrotrone Trieste, Area Science Park, 34012 Trieste, Italy — 2Centro Atómico Bariloche, 8400 S.C. de Bariloche, Argentina — 3CNR-Istituto dei Sistemi Complessi, 00016 Monterotondo (RM), Italy — 4Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria — 5Institute of Catalysis, Bulgarian Academy of Sciences, Sofia, Bulgaria — 6Physik-Dept.E20, TU Muenchen, 85748 Garching, Germany — 7Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany
With the well-known core hole clock method to measure charge transfer (CT) at surfaces by resonant core excitation and decay under resonant Auger Raman conditions (bandwidth of exciting photons below the lifetime width) the lifetimes of 4s electrons on core-excited Ar adsorbed on clean and H-covered n- and p-Si(100) have been determined. CT times are in the range of 1 to 4 fs. They do not depend on doping and are about twice larger on H-covered than on clean Si. Distinct structure is found as a function of excitation energy, similarly on both surfaces. It is explained by the influence of the empty band structure of Si(100), into which the excited 4s electron is transferred. The concepts and mechanisms will be discussed. Time allowing, the relation of this method to laser pump-probe techniques will be discussed.