Surface investigation of VUV-optical components after exposure to high-energy synchrotron radiation

In the framework of the European research project EUFELE, a set of fluoride and oxide single layer coatings was deposited, irradiated with synchrotron radiation, and subsequently thoroughly characterised. The observed coating damage is strongly related to the spatial distribution of the synchrotron radiation. Therefore, characterisation methods have to be adapted to techniques that are capable to reveal the structural and optical behaviour with adequate spatial resolution. A summary of the radiation damages of oxide materials (SiO2, Al2O3 and HfO2) produced by conventional and sputter deposition techniques, and of fluoride single layers (MgF2, LaF3, AlF3) deposited by thermal evaporation is presented. Degradation was observed within the irradiated areas as well as in the not directly exposed area. The observed degradation effects depend on the surface site. Oxide systems show a superior resistance compared to fluoride coatings. The most sensitive material is Lanthanum fluoride.