A NEW GENERATION OF X-RAY OPTICS BASED ON PYROLYTIC GRAPHITE

Highly Oriented Pyrolytic Graphite (HOPG) is a mosaic crystal, which consists of a large number of small nearly perfect crystallites. The unique structure of HOPG crys- tals enables them to be highly efficient in diffraction in an energy range between 2 keV up to several 10 keV. The mo- saicity of the crystal is responsible for the dramatic increase of integral reflectivity in comparison to perfect crystals. Furthermore thin HOPG crystal films can be easily bent and exhibit a very high thermal conductivity making them interesting for application in experiments with high average power x-ray sources. For application in x-ray spectroscopy the achievable spectral resolution of the crystal optics is of particular interest. Recently performed measurements with very low foil thickness have revealed a spectral resolution of E/ΔE = 2900 in (004)-reflection. This is by far the high- est spectral resolution reported for Pyrolytic Graphite (PG) crystals. The integral reflectivity of these films is still com- parable to that of ideal Ge crystals. In this work we present new results concerning the energy resolution, integral re- flectivity and application of thin bent Graphite films.