ABSTRACT
The first experimental results to our knowledge on the refractive index n = 1 - delta + ibeta of yttrium in the extreme-ultraviolet and soft x-ray energy ranges are discussed. To determine the absorptive part beta, transmittance measurements were performed on pure yttrium films in the 50-1300-eV energy region at beamline 6.3.2 of the Advanced Light Source. The dispersive part delta was then calculated from the absorption results by means of the Kramers-Kronig transformation. Compared with prior tabulated values, the new wet of data for the refractive index of yttrium is in better agreement with the sum rules and contains previously unresolved fine structure information in the regions of the M2,3 and M4,5 absorption edges, where yttrium-based multilayer mirrors operate.
ABSTRACT
The first experimental investigation of a normal-incidence Mo-Y multilayer-coated diffraction grating operating at a 9-nm wavelength is reported. The substrate is a replica of a concave holographic ion-etched blazed grating with 2,400 grooves/mm and a 2-m radius of curvature. The measured peak efficiency in the -3 order is 2.7% at a wavelength of 8.79 nm. To our knowledge, this is the highest normal-incidence grating efficiency ever obtained in this wavelength region.
