Monochromator operation in the carbon window region at the reflectometry beamline BL-11D of the Photon Factory

The vacuum ultraviolet (VUV) and soft X-ray beamline BL-11D of the Photon Factory has been recently equipped with a reflectometer to be dedicated to reflectometry for optical elements. The monochromator is of a varied deviation angle type. Focus conditions had been achieved using photoelectron spectroscopy data in the separated regions of 60–200 eV and 300–700 eV with respective gratings. Relying on the monochromator parameters, we programmed a monochromator operation optimized to 250-300 eV region for characterization of carbon window multilayers. Spectral reflectance of a Cr/C multilayer was measured at various angles of incidence, and the peak energy changed, showing that the monochromator has a good spectral accuracy as well as a high resolving power. We also programmed a monochromator operation above 700 eV, and the operable energy range has been extended to 200–1000 eV with one grating. The spectral transmittance and reflectances of Co/C multilayers were measured, and the spectral impurities were discussed.