Indices of refraction of ZnS,ZnSe, ZnTe,CdS, and CdTe in the far infrared

The indices of refraction of pure ZnS, ZnSe and ZnTe at 2, 80, and 300°K have been measured in the spectral region from 10 to 100 cm^-1. The indices of refraction can be described by the simple dispersion formula for an undamped harmonic oscillator. The static dielectric constants of these materials are obtained from the best fit parameters using a simple dispersion equation. The average indices of refraction of pure CdS and CdTe at 5°K in the spectral region from 10 to 100 cm^-1 have also been measured.