The optical properties of liquid germanium, tin and lead

Abstract

The optical constants of liquid germanium, tin and lead have been measured by a reflection method for wave numbers between 4000 and 27 000 cm⁻¹ (wavelengths 2·5 to 0·37 microns). The temperature variation of the optical constants was measured for tin and lead. The experimental results follow approximately the Drude free electron formulae if the number of free electrons per atom, N _o and their relaxation time, τ, are treated as adjustable parameters. The values of N _o lie between 4·3 and 4·7, with a slight temperature variation. The values of the static conductivity calculated from N _o and τ are compared with electrically measured values. Previous optical measurements on evaporated films of tin and lead have indicated values of N _o between 1·2 and 1·4 for the solid metals.