Abstract
The infrared reflection and transmission spectra of zinc selenide and zinc telluride were investigated at room temperature in the region of the transverse and longitudinal optical phonon frequencies. From the transmission measurements at oblique incidence of vacuum-evaporated films of these materials, the fundamental longitudinal optical (LO) vibration frequency could be obtained directly. Using the Lyddane-Sachs-Teller relation, the static dielectric constant was found to be 9.2 for ZnSe and 10.3 for ZnTe.