Ellipsometric measurement of the optical constants of solid and molten aluminum and copper at λ=10.6 μm

Abstract

The index of refraction, the extinction coefficient, and the absorptance were measured under ultrahigh vacuum conditions in a temperature range from 295 to 1000 K for aluminum and from 295 to 1400 K for copper for the CO2 laser wavelength at λ=10.6 μm. A photometric infrared ellipsometer was applied. The absorptance of the clean metallic surfaces jumps discontinuously from 3% to 7% in the case of aluminum and from 2% to 6% in the case of copper at the melting point. Calculations of the optical constants basing on the model of free electrons taking account of the effective mass and the anomalous skin effect describe the measurements for the solid state very well, but are less accurate for the molten state.