Temperature dependence of the infrared absorptivity of the noble metals

Abstract

The infrared absorptivity of the noble metals from 1.7 to 3.5 \ensuremath{\mu} has been measured in the range of 10 to 310 K. Electropolished bulk specimens of copper, silver, and gold and films evaporated onto polished sapphire have been studied. The results are interpreted in terms of the Holstein theories of phonon-assisted and surface-assisted absorption. These theories are found to provide an accurate description of the absorptivity, when allowance is made for anisotropy of the electron-phonon relaxation time over the Fermi surface. Values of this anisotropy are obtained. The average scattering of electrons at the metal surface is found to be nearly completely diffuse.