Comparison of the optical and dielectric properties of crystalline and molten lithium fluoride

Abstract

Experimental infrared emission and reflection measurements were made from 20-1000 cm-1 at temperatures 1115K and 1175K for LiF (melting point 1143K) and analysed by a combined classical oscillator and Kramers-Kronig procedure. The calculated optical and dielectric constants of molten LiF are presented; the shift in the frequency of maximum absorption reverses the trend exhibited by the solid as the temperature is raised. Comparison of the solid and molten far infrared emission spectra suggests the onset of low frequency transparency at approximately 120 cm-1 in the melt.