Temperature dependence of the i.r. optical properties of LiF∗

Essentially distortion-free imaginary dielectric index spectra have been obtained for LiF from Kramers-Kronig ( KK ) dispersion analysis of I.R. reflectance data at 300 K, 80 K and 20 K. The frequency dependence of the damping function as well as the temperature dependence of the various dispersion parameters of the first transverse optic mode have been illustrated. The effective damping constant \ gg o , and the resonance frequency ν o , are found to be in satisfactory agreement with the theoretical calculations.