The optics of the beamline combines a normal incidence (NIM) and a grazing incidence (PGM) monochromator to provide an efficient harmonic rejection at low photon energies.
|Monochromator||NIM + PGM with collimated beam|
|NIM||10 - 30 eV|
|PGM||20 - 800 eV|
Table 3: Optics parameters
The general concept of the SIS beamline in show in Figure 2. The first optical element is a sagittal mirror collimating the beam in the horizontal and vertical directions. The monochromator combines a normal incidence monochromator (NIM) and a plane grating monochromator (PGM). The collimated beam allows to vary the fix-focus constant Cff of the PGM as a free parameter without the need to move the exit slit. The NIM is used for the energy range of 10 - 30 eV and the PGM is used for 20 - 800 eV.