Soft X-ray spectroscopy of clusters, surfaces and interfaces

Atoms and Molecules

The studies on atoms and molecules concentrate on the response of matter to highly intense electromagnetic radiation in the soft x-ray regime and the work is mainly performed within the framework of the SFB 925 together with the group of M. Meyer from X-FEL. A close collaboration exist also with K. Tiedtke from Hasylab/DESY.

Highly intense x-rays are able to excite not only one, but several electrons withon an atom (or molecule) simultanously or sequentially creating highly excited states of matter. We are using photoelectron as well as photoion spectroscopy to study the electronic structure and the dynamic of the decay of these states.

Schematic view of an ion time of flight (iTOF) spectrometer

Time Resolved Studies

The XUV split-and-delay line developed in this group has been used to study multiphoton, nonlinear processes in Helium as well as Nitrogen. In Helium a two-photon double ionization process was used to determine the average pulse lengths of FLASH. A number as short as 30fs was found in 2008 as well as in recent measurements in 2012.
In Nitrogen we were able to see temporal coherence effects and to trace molecular dynamics of the double ionized Nitrogen molecule by observing the yield of double charged Nitorgen atoms as function of the delay.

 

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