Measurements of the optical constants of solid and molten gold and tin at λ=10.6 μm

Abstract

The index of refraction, the extinction coefficient, and the absorptance for gold and tin were measured in a temperature range from room temperature up to the melting point for the wavelength λ=10.6 μm. All measurements were performed under ultrahigh-vacuum conditions using a photometric infrared ellipsometer with a rotating analyzer. Measurements verify a discontinuous jump of the absorptance at the solid-to-liquid phase transition from 3.5 to 6.5% in the case of gold and from 4.9 to 9.2% in the case of tin. The experimental results derived for the clean solid surface are in good agreement with the theoretical prediction by a Drude model, if additionally appropriate effective masses and the anomalous skin effect are taken into account. This theory is much less accurate if applied to the molten state of gold and tin, as was already shown previously for liquid aluminum and copper.