Optical constants of arc-evaporated amorphous carbon in the far-infrared spectral region

Abstract

The optical constants $n$ and $k$ of arc-evaporated amorphous carbon films between 400 and 4800 ${\mathrm{cm}}^{\ensuremath{-}1}$ were determined by measuring the transmittance and the reflectance of the films. Two broad bands with maxima at 703 and 1233 ${\mathrm{cm}}^{\ensuremath{-}1}$ in the spectral dependence of the absorption index $k$ are interpreted as a disorder-induced absorption due to tetrahedrally coordinated carbon atoms. A shoulder extending to about 1650 ${\mathrm{cm}}^{\ensuremath{-}1}$ gives reason to believe that there is also a considerable amount of trigonally coordinated carbon atoms in the film.