Towards tender X-rays by means of multi-layer coated gratings as monochromator optics

Abstract Modern soft X-ray beamlines use collimated plane-grating monochromators (cPGM) [1] as monochromatization devices. Multilayer (ML)-coated plane gratings and mirrors allow to extend the available photon energy range of cPGMs towards the so-called tender X-ray photon energy range (up to 5keV), thereby achieving a significantly higher photon flux [2]. This X-ray energy range covers the L- and M-absorption edges of most transition and rare earth metals as well as the K-edges of lighter elements such as silicon, sulfur and phosphorus. Recently, such an ML-based monochromator setup was put into operation at the beamline U41-PGM1-XM at the storage ring BESSY-II in Berlin [3]. This beamline upgrade enables high-resolution spectromicroscopic applications with photon energies of up to 3keV and it is expanding its capabilities to support research in areas such as life sciences, semiconductor development and battery research. We report on the construction, commissioning and performance of this beamline and discuss possible options for new developments in the area of beamlines and end-stations in the tender X-ray energy range (up to 5keV) at existing and future new accelerator-based photon sources.