Reflectance spectrum of a diamond crystal measured between 200.0 and 610.0 eV is presented. The x-ray reflectance spectrum was combined with an earlier ultraviolet optical spectrum of diamond. Ex- trapolations to these reflectance spectra were calculated using a set of Lorentz oscillators. These reflectance values were used in obtaining the spectral dependence of the optical dielectric function of diamond via a Kramers-Kronig transform. The accuracy of these optical constants and the reflectance extrapolations were verified using optical sum rules. The refractive index of the diamond is found to be greater than unity near 287.0 eV.

• Received 15 October 1992

DOI:https://doi.org/10.1103/PhysRevB.47.3517