Alloy-ceramic oxide multilayer mirrors for water-window soft x rays

Alloy-ceramic oxide multilayers of Ni80Nb20-MgO with 3.56-nm period have be en made by use of the pulsed-laser deposition technique and characterized b y means of grazing-incidence x-ray reflectivity. The interface roughness wa s found to be only similar to0.35 nm at the two interfaces, Ni80Nb20-MgO an d MgO-Ni80Nb20, leading to a peak reflectivity of similar to 38% at the fir st order. The atomic structure in the two individual layers, Ni80Nb20 and M gO, is found to be amorphous, in agreement with the deposition conditions. These multilayers can be used as mirrors for soft x rays in the angular ran ge 18 degrees to 39 degrees depending on the actual wavelength of radiation in the water-window region. (C) 2001 Optical Society of America.