Absorption coefficients of reflecting surfaces of intermetallic compounds at the $\lambda=10,6\mu m$ wavelength

An experimental study was made of the dependences of the absorption coefficients on the chemical and phase composition of vacuum-condensed copper-tin alloys (with 17-60% Sn) and of the $\gamma$ phases of copper-aluminum and copper-gallium systems in bulk and thin-film forms. The minimum absorption coefficient, amounting to 2.1%, was obtained for the compound $Cu_3Sn$ with 38-40% Sn.