Ultrahigh resolution soft x-ray emission spectrometer at BL07LSU in SPring-8

An extremely high resolution flat field type slit less soft x-ray emission spectrometer has been designed and constructed for the long undulator beamline BL07LSU in SPring-8. By optimizing the ruling parameters of two cylindrical gratings, a high energy resolution Delta E < 100 meV and/or an E/Delta E similar to 10 000 are expected for the energy range of 350 eV - 750 eV taking into account the broadening by the spatial resolution (25 mu m) of a CCD detector. A coma-free operation mode proposed by Strocov et al., is also applied to eliminate both defocus and coma aberrations. The spectrometer demonstrated experimentally that E/Delta E = 10 050 and 8046 for N 1s (402.1 eV) and Mn 2p (641.8 eV) edges, respectively. (C) 2012 American Institute of Physics. [doi:10.1063/1.3680559]