Complete characterization of SU5 : a VUV high resolution beamline with variable polarizations

The SU5 VUV beamline aims towards a dual scientific program: high resolution spectroscopy on dilute targets and linear/circular dichroism on anisotropic systems. A crossed planar/helicoidal electromagnetic undulator has been designed and built, providing both flux and variable polarizations. We have shown a complete versatility of the polarization state of the emitted light with high polarization rates. Besides, the harmonics of the undulator can be suppressed owing to a gas filter, acting as a low-energy pass filter, with rejection factors above 105. The beamline is centered around a 6.65 m off-plane Eagle normal incidence monochromator which has shown unprecedented raw resolving powers (117 000 at 21.6 eV, 133 000 at 15.8 eV) with typical flux in a 1/50 000 bandwidth of 1010–109 photons/s between 6 and 30 eV