Düsseldorf 2007 – scientific programme

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SYSX: Symposium Soft X-ray induced ultafast processes on the atomic scale

SYSX 1: Soft X-ray induced ultrafast processes I

SYSX 1.3: Invited Talk

Thursday, March 22, 2007, 15:00–15:30, 6G

Interaction of clusters with intense soft x-ray radiation from the FLASH VUV-FEL — •Christoph Bostedt¹, Heiko Thomas¹, Ekaterina Eremina¹, Matthias Hoener¹, Hubertus Wabnitz², Tim Laarmann³, Rubens de Castro⁴, and Thomas Möller¹ — ¹TU Berlin, Germany — ²DESY, Hamburg, Germany — ³MBI, Berlin, Germany — ⁴LNLS, Campinas, Brazil

The interaction of rare gas clusters with intense vacuum ultraviolet radiation from the DESY free electron lasers has yielded many surprising results. In first experiments with 100 nm radiation unexpected high energy absorption involving plasma heating processes was measured and new theoretical explanations were suggested. The new DESY FLASH FEL delivers radiation down to first 32 and later also 13 nm wavelengths with intensities up to 10¹⁴ W/cm². We have performed first experiments with a combined time-of-flight spectroscopy and imaging approach. The new data give evidence that the dominant physical drivers in the light - matter interaction at reduced wavelength change and plasma heating is only of minor importance. At 32 nm the ionic fragments from the exploding clusters are ejected with only 25 eV and the electrons are emitted from the clusters serially. The atoms within the cluster move by only 3 Angstrom during the pulse duration making imaging experiments possible. At 13 nm wavelength first experiments about the ionization dynamics including core levels could be performed with Xe clusters. These measurements give some hints that the energy absorption involving core levels in the cluster may be reduced compared to atoms.