Resonant inelastic x-ray scattering (RIXS) is a photon-in/ photon-out technique, that was established as a powerful probe of the ground state of complex materials and chemical systems in the last years, as it is sensitive to various degrees of freedom of the electronic system, including charge, spin and orbital, as well as phonons. See poster 24 for first tr-RIXS results with hRIXS The intriguing physics of complex materials (e.g. superconductors) is governed by interactions between different degrees of freedom. Time-resolved RIXS (tr-RIXS) at Free-Electron-Lasers (FEL) enables to study how these subsystems are coupled (after excitations by an optical laser pump). Moreover, the dynamics of spin, charge, orbital and nuclear degrees of freedom are important in photo-chemical reactions. Left: RIXS spectra of antiferromagnetic Mott insulator La2CuO4 , measured at Cu L3 -edge (3,000 l/mm grating). The inset shows the scattering geometry. Right: elastic line measured close to specular condition. RIXS spectrum of liquid water in liquid-jet sample, measured at O K-edge (1,000 l/mm hRIXS grating). The inset shows zoom into the vibrational progression. Benchmarking with static RIXS data during commissioning of the hRIXS spectrometer in 2021/2022. The setup has been in regular user operation since 2022-II. Sample environment: XRD chamber and hRIXS spectrometer enable momentum resolved tr-RIXS studies from solid samples. The spectrometer can be moved on air cushions over the high-quality floor. Chemistry setup (CHEM) for liquid-jet samples and solid samples up to 10 -3 mbar: Cylindrical liquid jet, diameter of 20-50 µm Flat jet, 1-2 um sheet Solvents: liquid water, ethanol, isopropanol Sample catcher (new) Three 2Q angles: 90, 125 and 145 deg Sold sample holder Baseline SCS setup for x-ray resonant diffraction (XRD) at 10 -9 mbar (UHV): Cryogenic studies: 16 K – RT 6 degrees for freedom for the sample In-vacuum diffractometer (photodiodes, APDs) Triple-rotating flange (TRF), with continuous rotation in the horizontal plane In-vacuum breadboard Sample transfer Calculated efficiency of spectrometer gratings over the range of 250 eV – 1750 eV. The hRIXS spectrometer is holding two holographic gratings with line densities: 1,000 and 3,000 l/mm. The optical area of the gratings is 200 mm x 40 mm. Calculated bandwidth contributions for the two gratings. The assumed (vertical) source size is 5 µm and the detector pixel size (dispersion direction) is 10 µm. The User Consortium Heisenberg RIXS (hRIXS) spectrometer at the SCS instrument was proposed to be the first high-resolution soft x-ray RIXS spectrometer at an FEL. One aim is to explore the limits on energy and temporal resolution for tr-RIXS. While there is an intrinsic limit in quantum systems (Heisenberg limit), the FEL radiation also has limits, that will depend on the generation of the monochromatic beam. The SASE3 radiation at SCS instrument requires the use of a monochromator. For 10,000 energy resolving power the theoretical pulse width on the sample is around 80 fs at Cu L3 - and 150 fs at O K-edge. For 3,300 resolving power these numbers decrease by factor 3.