Sputtered V/Al2O3 multilayer x-ray mirrors for the water window

We report on a novel type of multilayer mirrors for the soft x-ray regime, namely V/Al2O3 layered stacks, grown on sapphire (11-20) substrates by RF sputtering techniques. Experimental reflectivities obtained with soft x-ray synchrotron radiation from the BESSY I are presented. For ([V(1.25nm)/Al2O3(1.27nm)]50 multilayer a normal incidence reflectance of 0.14 % is obtained at 247.5 eV and measurements at an energy close to the L3 edge of V yielded reflectance up to 18 % (θ = 27.9°)