The optical properties of the noble metals

This paper discusses the theoretical implications of results reported previously for the complex dielectric constant of copper and gold in the ultra-violet. The measurements allow one to deduce the optical effective mass of the conduction electrons. It is shown that the experimental far ultra-violet absorption spectrum results from excitation of tightly-bound d electrons. Comments are made on the problem of assigning the low-energy structure in the absorption spectrum to particular excitations in k space.