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Institute Methods and Instrumentation for Synchrotron Radiation Research

Spinresolved Electron Spectroscopy

Recent advances in the design of electron energy analyzers and spin detectors allow for an increase in transmission of instruments for spin-resolved photoemission by several orders of magnitude. This new generation of spectrometers will allow for the first time to probe radiation-sensitive samples like organic semiconductors and spintronics materials as well as correlated materials, which alter their properties due to photo doping. For radiation-hard materials, on the other hand, the acquisition time can be reduced drastically. This is particularly useful for reactive samples, which degrade even in ultrahigh vacuum on time scales shorter than what a traditional experiment would require. These new instruments are based on the time-of-flight scheme and require x-ray pulses with a temporal separation of the order of 1 micro-second as they are available in the single-bunch operation mode of BESSY II. With a new generation of MHz-Choppers such time structure can be generated out of the standard hybrid operation mode of BESSY II, which will increase the amount of beam time available for time-of-flight spectroscopy drastically. The free branch of the new Russian-German undulator beam line has been especially designed to fit such a chopper and a funding proposal to install a dedicated instrument for ultrahigh-transmission spin- and angle-resolved photoemission at this branch has been submitted by a consortium of German and Russian research groups.