LAUSR

We developed a hard X-ray spectrometer for the purpose of measuring X-ray emission spectrum excited by using single X-ray free electron laser (XFEL) pulses. A highly oriented pyrolytic graphite (HOPG) crystal was placed in the von Hamos geometry to focus X-rays of the equal energy on a specific point in detector plane. The spectrometer was tested at PAL-XFEL using Ni and NiO films. The Ni $${K_{{\beta _{13}}}}$$ X-ray emission line excited by using a single X-ray pulse was successfully resolved. If the much weaker Ni $${K_{{\beta _{25}}}}$$ line is to be observed, data must be accumulated with a few thousands of X-ray pulses. The spectrometer energy resolving power, E/ΔE, was estimated to be 7500. This spectrometer can be utilized to conduct various X-ray emission and absorption measurements using XFELs.