Investigation of the Infrared‐Active Lattice Vibration in SrCl2

SrCl2, single crystals were grown by the Czochralsky method. Their reflectivity at 300 K and transmission at 4.2 K were measured for frequencies from 10 to 930 cm−1 and 10 to 150 cm−1, respectively. The reststrahl band found in the reflection spectrum has been analyzed by means of a classical oscillator model. In addition, a Kramers‐Kronig analysis was performed since a satisfactory fit could not be achieved with the classical model. The frequencies of the TO‐mode and the LO‐mode were determined to be 138 and 233 cm−1, respectively. A pronounced shoulder on the reststrahl band was observed as is also the case for CaF2, BaF2 etc. Its origin is discussed in terms of multi‐phonon processes. The results of the transmission measurements show that SrCl2, is transparent in the far infrared up to 110 cm−1 where the lattice absorption starts at 4.2 K.