A setup for hard x-ray time-resolved resonant inelastic x-ray scattering at SwissFEL

We present a new setup for resonant inelastic hard x-ray scattering at the Bernina beamline of SwissFEL with energy, momentum, and temporal resolution. The compact R = 0.5 m Johann-type spectrometer can be equipped with up to three crystal analyzers and allows efficient collection of RIXS spectra. Optical pumping for time-resolved studies can be realized with a broad span of optical wavelengths. We demonstrate the performance of the setup at an overall similar to 180 meV resolution in a study of ground-state and photoexcited (at 400 nm) honeycomb 5d iridate alpha-Li2IrO3. Steady-state RIXS spectra at the iridium L-3-edge (11.214 keV) have been collected and are in very good agreement with data collected at synchrotrons. The time-resolved RIXS transients exhibit changes in the energy loss region