Multilayer-coated soft x-ray diffraction gratings for synchrotron radiation applications

We report about the diffraction efficiencies of two new types of multilayer diffraction gratings, one of them being proposed for high spectral dispersion ability due to a high line density in the photon energy range around 90 eV, while the other is being proposed as a multilayer grating working in the water window spectral range around 470 eV at near normal incidence angles. For a 6600 L/mm sinusoidal interference grating coated with 18 Mo/Si doublelayers of d = 8.2 nm absolute diffraction efficiencies up to 11 % at a wavelength lambda = 13.2 nm were measured in each first diffraction order. A 2400 L/mm laminar grating was coated with 60 Ti/C bilayers of d = 2.2 nm for high efficiency in the water window spectral range near the TI-L edge (lambda = 2.77 nm). For a similar Ti/C multilayer mirror reflectivities of 11 % were measured at a wavelength lambda = 2.7 nm and an angle of incidence alpha = 59 deg. First order diffraction efficiencies of about 0.7 % were measured for the Ti/C multilayer grating.