Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 30: New Perspectives of Scattering at Soft Matter

CPP 30.9: Vortrag

Mittwoch, 28. März 2012, 17:45–18:00, C 264

Observing Molecular Reactions via Simultaneous Ultrafast X-ray Spectroscopies and Scattering — •Wojciech Gawelda, Andreas Galler, Enrique Cuna, and Christian Bressler — European XFEL, Albert-Einstein-Ring 19, 22761 Hamburg

Structural dynamics research on chemical and biological systems seeks to extend the use of optical probes to the atomic-scale sensitive tools with either x-ray absorption spectroscopy (XAS) or x-ray (and electron) scattering (XRS). These tools were developed at synchrotron radiation sources, and thus ultimately limited to 50-100 ps time resolution due to the x-ray pulse widths.

We have recently succeeded to extend the capabilities of such laser-x-ray studies towards MHz pump-probe repetition rates at different synchrotron radiation sources, with quasi-static S/N. We studied different Fe-based spin transition compounds, via XAS, but now also with x-ray emission spectroscopy (XES) and XRS in one single setup. XES is sensitive to the actual spin state of the system, and XRS allows investigating the global structural environment of the thermally equilibrated sample. In addition, the electron transfer between a Ru-donor and a Co-acceptor atom was observed via TR-XES in a bimetallic bpy-based Ru-Co complex.

More intense xray pulses from x-ray free electron lasers (XFELs) are required in order to permit simultaneous femtosecond scattering and spectroscopic studies. This was done for the first time in liquid solutions of Fe-based spin transition compounds at the XPP end station of the LCLS, next to a Ru-Co based compound, and results discussed.