Ultrafast non-equilibrium dynamics studies aim at controlling material properties near ultimate speed and efficiency limits, developing novel concepts for faster and more efficient devices. Particularly for ultrafast spin dynamics, the present BESSY II Femtoslicing beamline is a world-wide unique research tool, albeit with a rather low energy resolution. Very recent experimental and theoretical work show that higher energy resolution is highly desirable to track not only spin but also electronic excitations and explore spatial inhomogeneity; both seem to play crucial but so far largely unexplored roles in magnetic dynamics. FemtoSlicing-HR aims at enabling these studies. Uniqueness: The Femtoslicing facility is optimized for magnetic dynamics studies with soft X-rays. As the time structure of competing Free Electron Lasers (FELs) is not well matched, the quality of magnetic dynamics data from FELs is no better than that from Femtoslicing. Uniquely, FemtoSlicing-HR benefits from the optimised research environment for spin and electronic dynamics experiments developed at BESSY II. Laser-based sources for the VUV range, the other competitor, do not provide the needed spectroscopic sensitivity; soft X-ray pulses are the probe of choice. Partners: HZB, FU Berlin
