Hannover 2013 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 36: Atomic clusters II (with MO)
A 36.2: Vortrag
Donnerstag, 21. März 2013, 14:30–14:45, F 428
Time resolved ionization dynamics of Xe clusters investigated with XUV-NIR pump-probe experiments at the FLASH free-electron laser — •M Sauppe1, M Adolph1, L Flückiger1, T Gorkhover1, D Rupp1, S Schorb2, S Düsterer3, M Harmand3, R Treusch3, C Bostedt2, M Krikunova1, and T Möller1 — 1IOAP, TUB — 2LCLS, SLAC — 3HASYLAB, DESY
Clusters irradiated by intense femtosecond extreme ultraviolet (XUV) light pulses from the FLASH free-electron laser are transformed into a highly excited non-equilibrium state resulting in complex electron and expansion dynamics. We used XUV and near infrared (NIR) pulses with pump-probe technique in order to get insight into the dynamics. The XUV pump pulse creates a nanoplasma of quasi-free electrons and initiates the expansion process of the cluster. The dynamics is probed with the time delayed NIR pulse.
Xenon clusters were produced by supersonic expansion of Xe gas. Ions and scattered photons from large single xenon clusters were recorded in coincidence. The scattering pattern gives us the possibility to determine and sort for cluster size. With the expansion of the clusters, the density of the generated quasi-free electrons of the produced nano plasma decreases. At well defined delay after the first pulse, the resonant frequency of the nanoplasma meets the frequency of the NIR-probe pulse, known as plasma resonance. These optimal conditions for energy absorption from the NIR pulse into the cluster lead to a simultaneous increase of the ion yield as observed in our experiment. The relationship between cluster size and ion yield will be discussed.