High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (R1XS) and angle-resolved photoelectron spectioscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0-180 rotatable lineal polarizations) but also the energy without changing the gap The beamline optics is based on the well established scheme of planegrating monochromatoi operating in collimated light. The ultimate resolving power E/AE is above 33000 at 1 keV photon energy The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the minors as well as optimized groove densities and profiles of the gratings. the beamhne is capable of delivering high photon flux up to 1 x 10" photons (0.01% BW)-I at 1 keV. Ellipsoidal refocusing optics used for the R1XS endstation demagmfies the vertical spot size clown to 4 pm, which allows shtless operation and thus maximal transmission of the highresolution R1XS spectrometel delivering E/6,E > 11000 at 1 keV photon energy. Apart from the beamhne optics, an overview of the control system is given. the diagnostics and software tools are described, and strategies used for the optical alignment are discussed An introduction to the concepts and instrumental realisation of the ARMES and RIXS endstations is given