Hamburg 2009 – wissenschaftliches Programm

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SYUF: Ultra-fast Dynamics in FEL Light Pulses

SYUF 1: SYUF I

SYUF 1.1: Hauptvortrag

Mittwoch, 4. März 2009, 14:00–14:30, VMP 8 HS

Atoms and molecules in intense FEL radiation — •Artem Rudenko — Max Planck Advanced Study Group at CFEL, Nottkestrasse 85 22607 Hamburg

The emission of few electrons from atoms, molecules, clusters or solids constitutes one of the most fundamental processes occurring when intense VUV or X-ray radiation interacts with matter, underlying essentially all practical applications of free-electron lasers. Recent development of the Free electron LASer in Hamburg (FLASH) along with the progress in high-harmonics generation made multi-photon multi-electron transitions in this energy range experimentally accessible, triggering enormous theoretical interest and opening the way for a variety of time-resolved imaging schemes. Here an overview of recent experimental studies on few-photon-induced fragmentation of rare gas atoms and simple diatomic molecules performed at FLASH employing coincident cold-target recoil ion and electron momentum spectroscopy will be presented. Particular examples include a disentanglement of sequential and direct ('non-sequential') mechanisms for few-photon double ionization of Ne and He atoms, identification of different dissociation and Coulomb explosion pathways in FEL-induced fragmentation of N2, O2, D2 molecules, and the results of the first VUV-VUV pump-probe experiments. The latter measurements not only allow for a time-resolved mapping of fragmenting molecular states, but also yield valuable information on the properties of the FEL pulse via channel-selective analyses of autocorrelation-like patterns.