Reflection Measurements on Reststrahlen Crystals in the Far-Infrared Region

Abstract

The reflectivities of various reststrahlen crystals were accurately measured or remeasured in the far-infrared region. The crystals measured were NaF, CaF2, BaF2, NaCl, KCl, KBr, KI, CsBr, CsI, TlCl, TlBr, KRS-6, and KRS-5. A side band was newly observed for each of BaF2, Kl, CsBr, and CsI. Reflectivities of NaCl, KCl, and KBr were also measured at temperatures of 100° and 200°K. As the temperature decreased, the peak reflectivity increased with an overall shift of the band to the shorter-wave side.