Berlin 2015 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 115: Metallic Nanowires on the Atomic Scale (jointly with DS, O)
TT 115.4: Vortrag
Freitag, 20. März 2015, 10:30–10:45, H 2032
Ultrafast dynamics of (quasi-1D) Pb overlayers grown on flat and vicinal Si(111) — •Abdul Samad Syed1, Vesna Mikšić Trontl1, Manuel Ligges1, Mathias Sandhofer1, Ishita Agarwal1, Isabella Avigo1, Daniel Lükermann2, Christoph Tegenkamp2, Herbert Pfnür2, and Uwe Bovensiepen1 — 1Fakultät für Physik, Universität Duisburg-Essen — 2Institut für Festkörperphysik, Leibniz Universität Hannover
Due to real space anisotropy of the vicinal Si(111) surfaces, hot electrons can be expected to exhibit different dynamics along and perpendicular to the steps [1] as compare to the Si(111) flat surface. We made a comparative study of Pb overlayer structures grown on vicinal Si (557) and flat Si (111) using femtosecond time- and angle- resolved two-photon photoemission. We mapped the unoccupied electronic band structure near Γ and find that both systems have two unoccupied states at E−EF=3.3 and 3.5 eV. In pump-probe experiments combined with a position sensitive electron time of flight spectrometer we analyze the ultrafast momentum dependent electron dynamics along two in plane directions. On vicinal surfaces we observe a specific, momentum dependent population dynamics which are absent on the flat surface. This signature shows a delay in population build up of 5 fs as a function of angle with respect to the terrace direction. We assign this behavior to step-induced scattering. We gratefully acknowledge funding by the DFG through FOR1700.
[1] Roth et al., Phys. Rev. Lett. 88, 096802 (2002)