Stuttgart 2012 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 39: Poster: Atomic clusters
A 39.6: Poster
Donnerstag, 15. März 2012, 16:30–19:00, Poster.V
Collective electron dynamics in xenon clusters, studied with XUV-IR pump-probe experiments at FLASH
— •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
Femtosecond short and intense light pulses are able to transform matter into a highly excited non-equilibrium state. Clusters, exposed to short and intense XUV pulses reveal complex electron and nuclear dynamics. By using XUV radiation from FLASH synchronized to IR pulses in pump-probe configuration it is possible to gain information about the expansion and desintegration dynamics of the clusters. In our setup the XUV pump pulse creates a nano plasma of quasi-free electrons and the cluster expansion process is iniciated. The time delayed IR pulse probes the dynamics of the quasi-free electrons.
The clusters were produced by supersonic expansion of xenon gas into vacuum. We recorded ions and scattered XUV photons of single clusters simultaneously. The scattering pattern allows us to sort for cluster size. In the produced nano plasma the density of the generated quasi-free electrons decreases with the cluster expansion. At some point the plasma frequency gets in resonance with the frequency of the IR pulse. This results in optimum condition for energy absorption of cluster for which reason the degree of cluster ionization and fluorescence yield on the scattering pattern increases substantially. We discuss the relationship between cluster size and delay time.