Surface Science Studies with Free Electron Lasers: Real-Time Observations of Electronic Structure Changes during Reactions

Abstract

New light sources based on linear accelerators such as FLASH at DESY in Hamburg, the first free-electron laser in the extreme ultraviolet (XUV) and soft X-ray regime, which started user operation in 2005 [1], the Linac Coherent Light Source LCLS in Stanford [2], and SACLA at Spring-8 in Japan [3], as X-ray lasers dedicated to the hard X-ray regime down to below 1 Å in wavelength, or FERMI at ELETTRA in Trieste [4] as the first fully externally seeded free electron laser also operating in the XUV and soft X-ray regime, provide ultrashort, extremely powerful, short wavelength pulses with unprecedented coherence properties. With the European XFEL in Hamburg, the Swiss FEL at PSI in Villigen, Switzerland, and the PAL-XFEL in Pohang, Korea, three more FELs are expected to produce first light by the end of 2016 and the beginning of 2017, respectively.

Acknowledgements

I would like to acknowledge the staff of LCLS and FLASH for their fantastic support during several beamtimes. In addition, the contribution of all collaborators in the respective experiments has been absolutely essential in obtaining the results discussed. The respective names can be found in the cited publications. Here, I would only like to mention Anders Nilsson, Lars Pettersson, and Jens Norskov as the leading persons behind the experimental and theoretical efforts, respectively, in the surface science collaboration at LCLS and, in particular, Martina Dell'Angela, Martin Beye, Hirohito Ogasawara, and Henrik Öström, who have been really driving the experiments.

Funding

The activities of my group in Hamburg have been supported by the German Ministry for Education and Science through the priority programs FSP-301: “FLASH: Matter in the Light of Ultrashort, Extremely Intense X-ray Pulses” and FSP-302: “Free-Electron Lasers,” as well as through the Cluster of Excellence CUI “Hamburg Center for Ultrafast Imaging” funded as part of the Federal Excellence Initiative by the German Research Foundation DFG.