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O: Fachverband Oberflächenphysik
O 43: Poster Session II - MA 141/144 (Surface Spectroscopy on Kondo Systems; Frontiers of Surface Sensitive Electron Microscopy; Methods: Scanning Probe Techniques+Electronic Structure Theory+Other; Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation; joined by SYNF posters)
O 43.43: Poster
Dienstag, 26. Februar 2008, 18:30–19:30, Poster F
A femtosecond X-ray/optical cross-correlator: Free-electron laser X-ray pulse induced transient optical reflectivity — •Cornelius Gahl1,4, Armin Azima3, Martin Beye2, Martin Deppe2, Kristian Döbrich1, Urs Hasslinger2, Franz Hennies2,5, Alexej Melnikov1, Mitsuru Nagasono2, Annette Pietzsch2, Martin Wolf1, Wilfried Wurth2, and Alexander Föhlisch2 — 1Fachbereich Physik, Freie Universität Berlin — 2Institut für Experimentalphysik, Universität Hamburg — 3HASYLAB/DESY, Hamburg — 4Max-Born-Institut Berlin — 5MAX-lab, Lund Universitet, Sweden
Due to their short pulse duration and high brilliance over a wide range of photon energies free-electron-laser (FEL) based femtosecond x-ray pulse sources make possible completely new classes of experiments. Since it is extremely difficult to precisely synchronize a FEL with an external femtosecond laser source, one has to measure the relative arrival time of x-ray and optical pulse to perform pump-probe experiments with optimal time resolution. At the Free-Electron-Laser in Hamburg (FLASH) we exploited the high peak brilliance for this purpose by measuring the x-ray induced transient change in optical reflectivity at a GaAs surface. The ultrafast drop in reflectivity on the time scale of the pulse duration enables us to determine the temporal overlap of x-ray and optical pulses as well as the statistical timing jitter and a systematical drift within a pulse train. Therefore this easy to implement technique denotes an important step towards delay control for femtosecond time-resolved experiments and opens up the field of femtosecond X-ray induced dynamics.