Düsseldorf 2007 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 24: Poster II - Interaction with VUV and X-ray light

A 24.2: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster B

Quantum dynamics in atomic and molecular fragmentation by strong FLASH pulses — •Y. H. Jiang¹, R. Moshammer¹, L. Foucar², A. Rudenko¹, Th. Ergler¹, C.D. Schröter¹, S. Lüdemann¹, K. Zrost¹, D. Fischer³, J. Tietze², T. Jahnke², M. Schöffler², T. Weber^2,4, R. Dörner², T. Zouros⁵, A. Dorn¹, T. Ferger¹, K.U. Kühnel¹, J. Ullrich¹, R. Treusch⁴, P. Radcliff⁴, and E. Plönjes⁴ — ¹Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg — ²Institut für Kernphysik, Universität Frankfurt, D 60486 Frankfurt — ³Stockholm University, Stockholm — ⁴DESY, Notkestrasse 85, 22607 Hamburg — ⁵University of Crete, Greece

Few-photon multiple ionization of Ne and Ar atoms as well as D₂ molecule by strong VUV laser pulses from the Free electron LASer at Hamburg (FLASH) was investigated differentially with the reaction microscope. The light of wavelengths 44 nm and 32 nm, a pulse duration of ≈ 50 fs, at pulse energies ≈3-10 µ J, allows to observe few-photon multiple ionization of atoms and molecules The light intensity dependence of ion production yields reveals the dominance of non-sequential multi-photon ionization mechanisms at relative low intensities. Recoil ion momentum spectroscopy of Ne²⁺ shows for the first time that two electrons absorbing "instantaneously" two photons are ejected most-likely into opposite hemispheres with very similar energies, a situation that is strongly different in single photon double ionization or even forbidden for equal energies in strictly opposite direction.