Düsseldorf 2007 – wissenschaftliches Programm
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SYSX: Symposium Soft X-ray induced ultafast processes on the atomic scale
SYSX 2: Soft X-ray induced ultrafast processes II
SYSX 2.1: Hauptvortrag
Donnerstag, 22. März 2007, 16:30–17:00, 6G
Atomic photoionization by femtosecond soft X-ray pulses — •Mathias Richter1, Sergey V. Bobashev2, Andrei A. Sorokin1,2, Kai Tiedtke3, Hubertus Wabnitz3, and Michael Wellhöfer4 — 1Physikalisch-Technische Bundesanstalt, PTB, Abbestraße 2-12, D-10587 Berlin, Germany — 2Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg, Russia — 3Deutsches Elektronen-Synchrotron, DESY, Notkestraße 85, D-22603 Hamburg, Germany — 4Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
The contribution refers to recent results on atomic photoionization obtained in focused photon beams at the new free-electron laser (FEL) in Hamburg (FLASH) by ion time-of-flight mass/charge spectroscopy. The experiments were performed with emphasis on a quantitative determination of pulse energy in the order of 10 microjoule and focus diameter down to 3 micrometer which yields, together with the estimated pulse duration of 10 to 30 fs, irradiance levels of up to 1e16 W/cm2 achieved. Strong non-linear behavior due to multi-photon processes was observed on helium, neon, and xenon atoms studied as a function of photon intensity. Results are discussed with regard to the role of sequential and direct multi-photon ionization and a theoretical description by perturbative and non-perturbative methods.