Hamburg 2009 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 23: Molekülphysik Poster 2
MO 23.10: Poster
Donnerstag, 5. März 2009, 16:30–19:00, VMP 8 Foyer
Characterization and optimization of a femtosecond high-order harmonic VUV photon source for investigating ultrafast molecular dynamics — •Torsten Leitner1, Philippe Wernet1, Kai Godehusen1, Olaf Schwarzkopf1, Tino Noll1, Jerome Gaudin3, Andrei Sorokin2, Henrik Schoeppe2, Mathias Richter2, and Wolfgang Eberhardt1 — 1Helmholtz-Zentrum Berlin - Elektronenspeicherring BESSY II — 2Physikalisch-Technische Bundesanstalt, Berlin — 3DESY/ European XFEL Project Team, Hamburg
High-order harmonic generation (HHG) with femtosecond lasers in rare gas media has recently emerged as a promising tool to produce bright atto- and femtosecond vacuum-ultraviolet and soft x-ray pulses. These pulses can be used to study ultrafast molecular dynamics in a pump-probe electron spectroscopy configuration. To allow for appropriate experimental conditions the key parameters of the photon source like flux, spot size and shape have to be optimized. This was done in recent experiments at the BESSY femtosecond HHG source. A Gas Monitor Detector was used to investigate the absolute photon flux of the source and validate the photon numbers derived from a calibrated GaAsP diode. The beam divergence and transverse shape were investigated with a CCD camera showing, that optimizing the source to the highest photon flux does not necessarily result in optimal transverse beam profiles as needed for further pump-probe experiments on molecular dynamics. Therefore the experimental setup was extended by a quasi-online monitoring system enabling fast optimization of the light source.