Optical constants of materials for multilayer mirror applications in the EUV soft x-ray region

Sum rule tests demonstrate that there are deficiencies in the available optical data for materials important in multilayer mirror applications, such as Si and Ma, leading to errors in the estimation of the real and imaginary parts of the refractive index n = 1 - delta + i beta (delta, beta are also known as ''optical constants''). The refractive index of Si is investigated in the region 50-180 eV using angle dependent reflectance measurements. It is shown that the reflectance method has limited efficiency in certain energy regions. Transmission measurements for the refractive index of Mo are performed in the energy range 60-930 eV. The new experimental results are used in order to form an improved, self-consistent database for the real and the imaginary part of n for Si and Mo and they are compared to the values in the 1993 atomic tables. The normal incidence reflectivities of Mo/Si and Mo/Be multilayer mirrors are calculated using the new results.