Chinese Acad Sci, Inst Phys, Beijing 100080, Peoples R China
; Chinese Acad Sci, Ctr Condensed Matter Phys, Beijing 100080, Peoples R China
; Beijing Univ Sci & Technol, Dept Phys Mat, Beijing 100083, Peoples R China
; Beijing Lab Electron Microscopy, Beijing 100080, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
The optimal reflectivity of soft-x-ray multilayers made of new pairs of materials was theoretically calculated in the wavelength range of 2.0-4.5 nm. Molybdenum and silicon dioxide were then selected for "high index'' and "low index'' layer, respectively, in the multilayer system. The microstructures and composition profiles of multilayers of molybdenum and silicon dioxide were investigated by means of low-angle x-ray diffraction, cross-sectional high resolution electron microscopy, an energy-filtering transmission electron microscope elemental mapping, and Auger electron spectrometry. The results show that no diffusion of Si into Mo layers has occurred, and only slight diffusion of O into Mo layers are seen. Sharp and relatively smooth interfaces have formed. With increasing number of layers, the interfacial roughness was propagated through the multilayer stack and low-frequency roughness increases while the high-frequency roughness decreases. (C) 1999 American Institute of Physics. [S0021-8979(99)00406-5].