Optical Properties of Graphite in the Region 1100 to 3000 Å

Abstract

The optical properties of hot-pressed pyrolytic graphite were studied in the wavelength region from 1100 to 3000 \AA{}. The real ($n$) and imaginary ($k$) parts of the complex index of refraction were obtained from reflectance measured at 20\ifmmode^\circ\else\textdegree\fi{} and 70\ifmmode^\circ\else\textdegree\fi{} incidence. The complex dielectric constant and the energy-loss function were determined from these values of $n$ and $k$. The energy-loss function, $\mathrm{Im}(\frac{1}{\ensuremath{\epsilon}})$, was found to exhibit a maximum at a wavelength of 1800 \AA{} corresponding to an energy of 6.9 eV. This peak corresponds to the 7.5-eV loss in electron energy-loss experiments, where it has been attributed to the excitation of the conduction-electron plasma.