Light scattering spectrum of disordered molecular crystals: KCN

We have investigated the effect of the low temperature order-disorder phase transitions on the Raman spectrum of KCN. In the disordered cubic room temperature phase we only find a broad central component in the spectrum which sharpens near the transition temperature at 168K. From the doubling of the librational mode of the CN^--molecules we conclude that an antipolar orientation of the CN^--molecules is probable for the low temperature phase below 83 K.