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The optical absorption spectrum of the H2S molecule in the region from 2050 to 1150 Å has been studied by a photographic method, using the radiation from a 1.3-GeV electron synchrotron as a background source. Numerous bands including those due to dipole forbidden transitions are observed in the spectrum. Five types of Rydberg series are assigned to electronic transitions from the outermost 2b1 orbital to the d-like orbitals, three types to the p-like orbitals, and one type to the s-like orbital. The quantum defects of these transitions and a series limit of 84 417 ± 8 cm−1 (10.466 ± 0.001 eV) were determined using the extended Rydberg series. The first member of the A Rydberg series splits into four bands, which is discussed with jj coupling scheme. The upper state of the 2000-Å (6.20-eV) broad band is assigned to the (2b1)−1 (6a1/4sa1) 1B1 state which is predominantly of valence orbital character. Transitions to vibrationally excited state were also investigated and the limit to which the (100) vibrationally excited Rydberg series converges was determined to be 86 882 ± 20 cm−1 (10.772 ± 0.003 eV). The results obtained in this experiment are compared with theoretical calculations.

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Performance tests were carried out on a varied line-spacing plane grating monochromator at BL27SU of SPring-8 in the higher energy region using photoabsorption spectra of gas and solid samples and photoelectron spectra of Xe 5p 3/2 . A flux of 1ϫ10 11 photons/s/100 mA/0.02% b.w. was achieved at 2 keV. The photon flux steeply decreased above 2 keV to 5ϫ10 9 photons/s/100 mA/0.02% b.w. at 2.8 keV.

A spectrometer for soft X-ray emission spectroscopy was designed and constructed. The aims of this spectrometer are high detection efficiency and realizing the energy resolution of 1000 (E/ΔE) in a compact size. To satisfy these requirements, a flat field spectrometer with a varied line spacing grating and a CCD detector was chosen. Furthermore, the configuration without the entrance slit was employed. For compact flat field spectrometers, the spectral dispersion on the detector is sometimes smaller than the spatial resolution of existing detectors restricting maximum energy resolution. The spectral dispersion on the detector was optimized to balance with the spatial resolution of CCD. Optical performance was tested with a ray-tracing program. The spectrometer covers 250–900 eV, with two gratings. Taking into account the spatial resolution of a CCD detector, the maximum energy resolution of the spectrometer is estimated to be about 1000 (E/ΔE) for the beam size of 10 μm. Using the constructed spectrometer, test experiments were performed at the beamline BL27SU in SPring-8.