Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/[B.sub.4]C multilayer

Soft-x-ray Bragg reflection from two Ru/[B.sub.4]C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 - [delta] + i[delta] close to the boron K edge (~188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to [B.sub.4]C and various boron oxides. OCIS codes: 120.4530, 310.6860, 340.7470.