Design of the high-resolution BUS XUV-beamline for BESSY II

We present the design characteristics of an XUV undulator beamline for BESS Y II, based on a spherical-grating monochromator for the energy range from 35-500 eV. The monochromator will use a moveable pre-mirror and a moveable exit slit and has been optimized for highest resolution. For photon energie s up to 200 eV a resolving power of 50 000 up to 80 000 should be achievabl e, and for higher energies a resolving power of 20 000. All properties of t he beamline have been extracted from ray-tracing calculations taking slope errors as well as the characteristics of the source into account. (C) 1999 Elsevier Science B.V. All rights reserved.