Far-Infrared Reflectance and Transmittance of Potassium Magnesium Fluoride and Magnesium Fluoride

Abstract

The room-temperature transmittance of KMg${\mathrm{F}}_3$ and Mg${\mathrm{F}}_2$ have been measured from 800 to 70 ${\mathrm{cm}}^{-1\mathrm{}}$. Reflectance measurements were made over a wider range in the far infrared and the data have been analyzed using the Kramers-Kronig relationship to obtain the dielectric dispersion of these materials. Three resonances were observed for KMg${\mathrm{F}}_3$ and four were observed for Mg${\mathrm{F}}_2$ as required by standard group theory and these have been related to presumed normal modes of vibration of the crystals.