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

It is reported on a novel type of multilayer mirrors for the soft X-ray regime, namely V/Al2O3 layered stacks grown on sapphire (1 1 2̄ 0) substrates by RF sputtering techniques. Experimental reflectivities obtained with soft X-ray synchrotron radiation from the BESSY I are presented. For a [V(1.25 nm)/Al2O3(1.27 nm)]50 multilayer a normal incidence reflectance of 0.14% is obtained at 247.5 eV and a reflectance of 18% (θ=27.9°) is yielded at an energy close to the L3 edge of V.