Soft x-ray RIXS endstation at Sirius

Resonant Inelastic X-ray Scattering (RIXS) stands out as a versatile technique to probe the electronic structure and excitations of materials in gas, liquid and solid state. It is a unique tool for studying low energy excitations in complex correlated systems, being directly sensitive to charge-, orbital-, spin-, and lattice- degrees of freedom of solids. For molecular systems, RIXS provides unique possibilities to study ultrafast phenomena and measure element and mode selective potential energy curves for both ground and excited states. This valuable tool will be soon available at the IPE beamline of Sirius, the 4th generation synchrotron source under construction at Campinas, Brazil. In this work, we report the spectrometer optical design based on a cylindrical variable line spacing grating and an electron multiplying CCD detector. We present the performance calculations based on ray-tracing, which indicate a resolution 23 meV at a reference energy of 930 eV. Moreover, we show the mechanical design of the spectrometer and experimental chambers together with structural calculations based on finite element analysis to evaluate the mechanical stability of the endstation.