The beamline is purpose-built to provide high flux and resolution in the energy range from 5−200 eV. The light source is an APPLE2 undulator (UE112) that allows for full control over the polarization. Its light is further refined by a collimated low-energy plane grating monochromator that can be operated with either a 600 or 2400 l/mm grating. A normal incidence option with a 2400 l/mm grating is available to retain intensity and polarization at the lowest energies. The monochromated light can be directed to either the right exit arm towards the 13 station, or the left branch towards 12. Resolving powers in excess of 100.000 have been demonstrated with the 2400 l mm−1 grating. However, the 600 l mm−1 grating provides ample resolution (> 20.000) and superior flux (1012−1013 photons s−1 0.1 A−1), which means it is used for most experiments.
Spot-sizes of 210 and 465 µm have been achieved on the right (13) and left (12) branch, respectively. An upgrade to improve the focus on the latter branch is planned in the nearest future.
• R. Follath, J. S. Schmidt, A grazing incidence monochromator for the photon energy range 5-250 eV, Proceedings of the Eighth International Conference on Synchrotron Radiation Instrumentation.
• R. Follath, The versatility of collimated plane grating monochromators, Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 418–425.