Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 90: Intersectional Joint Session: Nano Plasmonic

HL 90.4: Hauptvortrag

Freitag, 18. März 2011, 12:00–12:30, BAR 205

Coulomb complexes: Electron emission from clusters in strong FEL pulses — •Ulf Saalmann — MPI for the Physics of Complex Systems

The response of atomic clusters to short intense pulses at extreme-ultraviolet (XUV) and Xray wavelengths — as available from short-wavelength free-electron laser (FEL) sources like FLASH in Hamburg/Germany, the SCSS in Japan or LCLS in Stanford/California — is studied theoretically. Due to the high photon flux the clusters become multiply charged by massive electron emission. We device a model, which we call Coulomb complexes [1], in order to investigate the emission process. It turns out that the electron spectra strongly depend on the ionization rate. For low rates the electron release occurs sequentially and our model allows for an analytical description of the plateau-like electron spectra [1]. At high rates a dense nanoplasma is formed and ionization occurs through energy-exchanging collisions resulting in exponential electron spectra [2]. Both mechanisms can be understand in terms of our model containing only very few parameters available from experiments.
[1] Gnodtke, Saalmann, Rost, New J. Phys. in press (2011).
[2] Bostedt et al., New J. Phys. 12, 083004 (2010).