CXIV. Optical constants of metals in the infra-red-Conductivity of silver, copper and nickel

The experimental methods used to measure the optical constants of metals at infra-red frequencies have already been described. The conductivity of evaporated aluminium, silver, copper and nickel is reported. Since the penetration depth is small the behaviour is closely related to the nature of the surface of the metal; attention is therefore paid to the preparation of various representative surfaces including hand polished, electrolytically polished and those obtained by evaporating in vacuo. By giving care to the manner of presenting experimental results, the various factors which contribute to the absorption may be discriminated. Figures are given of relaxation times, conductivity and the effective number of free electrons per atom. Elementary interpretations are given.