Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 78: Graphene: Preparation and characterization I (O, jointly with HL, TT)
HL 78.4: Talk
Thursday, March 14, 2013, 11:15–11:30, H17
Dynamics of adsorbate layers on freestanding graphene probed by ultrafast low-energy electron diffraction — •Max Gulde1, Simon Schweda1, Manisankar Maiti1, Hakki Yu2, Sascha Schäfer1, and Claus Ropers1 — 1Materials Physics Institute and Courant Research Centre, University of Göttingen, Germany — 2Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, University of Göttingen, Germany
Ultrafast structural dynamics in solids and nanostructures can be observed by an increasing number of sophisticated electron and x-ray diffraction techniques. Despite successful implementations of ultrafast reflection high-energy electron diffraction (1,2), the diffractive probing of ultrafast structural processes at surfaces remains an experimental challenge. We have implemented ultrafast low-energy electron diffraction (ULEED) to study structural changes with high temporal resolution and ultimate surface sensitivity, at electron energies from 100 eV to 500 eV. Specifically, we ultilize nanoscopic needle emitters in an electrostatic lens geometry as high-brightness sources of pulsed electrons. With this approach, the ultrafast melting dynamics of ordered adsorbate structures on freestanding graphene is investigated in transmission with a temporal resolution below 5 ps.
(1) A. Hanisch-Blicharski, A. Janzen, B. Krenzer, S. Wall, F. Klasing, A. Kalus, T. Frigge, M. Kammler, and M. Horn-von Hoegen, Ultramicroscopy (accepted) (2012)
(2) S. Schäfer, W. Liang, and A. H. Zewail, J. Chem. Phys. 135, 214201 (2011)