The optical properties of pure liquid nickel and iron were investigated in the energy range 1.2–3.5 eV. Nickel and iron specimens were electromagnetically levitated, melted, and purified of residual oxide contaminants by heating to elevated temperatures and/or reacting the liquids with pure hydrogen. An automated dual-detector rotating analyzer ellipsometer with a pulsed-dye-laser light source was employed to measure the optical properties. Measurements were obtained over the full energy range at 1764 K for nickel and at 1890 K for iron. Liquid nickel exhibited a broad minimum in the optical conductivity at about 2.2 eV photon energy, similar to the minimum that the solid exhibits at about 3 eV. The optical conductivity of liquid iron increased smoothly from the UV to the IR except in the vicinity of 2.25 eV where a 10% decrease was observed. This behavior is quite different from the solid, which shows a broad peak in the optical conductivity at about 2.4 eV and decreasing conductivity values towards the UV and IR. A broad minimum was also observed in the real part of the dielectric constant for liquid iron, at about 2.0 eV, where a maximum occurs for the room-temperature ferromagnetic solid. The optical properties and spectral emissivities of liquid nickel and iron are discussed with respect to available literature data for both the solid and liquid.

DOI:https://doi.org/10.1103/PhysRevB.55.8201