X-ray absorption/fluorescence spectroscopy probes valence states relative to a core level and thus provides an absolute energy reference. The core hole lifetime broadening can be reduced by restricting the fluorescence signal with a sub-eV crystal energy analyzer. We describe the design and first performance tests of adaptive optics for a bent-crystal analyzer which is characterized by a high counting efficency and a large solid angle acceptance. The device was designed for the determination of charge carrier dynamics in photoexcited semiconductors in laser pump, x-ray probe experiments. It can also be used in a wide range of near-edge spectroscopic applications and as an ultrafast laser/x-ray cross correlator...
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