Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 57: Surface dynamics II
O 57.3: Vortrag
Mittwoch, 24. März 2010, 15:30–15:45, H40
Desorption of ionic species from ice/graphite by femtosecond XUV free electron laser pulses — •Björn Siemer1, Tim Hoger1, Robert Frigge1, Sebastian Roling1, Rolf Mitzner2, Rolf Treusch3, Stefan Düsterer3, and Helmut Zacharias1 — 1Westfälische Wilhelms-Universität, Münster,Germany — 2Helmholtz Zentrum Berlin, Berlin,Germany — 3DESY, Hamburg, Germany
The interaction of high-energy photons in the soft x-ray regime with surface systems may lead to new and unexpected results due to the large number of accessible product states. In the past this photon energy regime has mainly been investigated using synchrotron radiation sources. The development of the Free Electron Laser at Hamburg (FLASH) now opens a new area in this spectral range. It provides pulsed radiation in the photon energy range from 20 to 200 eV, with pulse energes of tens of microjoule and a pulse duration of 20 to 50 fs.
We want to present first results from our recent measurement session. Highly-oriented pyrolytic graphite (HOPG) surfaces covered with D2O are irradiated and desorbing products are analyzed. Ionic species are formed by the FEL radiation on the surface and directly emitted from the graphite. The O2+ yield shows a highly nonlinear dependence on the FEL intensity. This opens the way to non-linear correlation measurements with an autocorrelator using two FEL pulses synchronized on a femtosecond time scale. First results from these two-pulse correlation measurements in the soft x-ray regime are reported.