Detailed Raman scattering investigation of LiKSO₄ in phases II and III across the transition temperatureT_c ≃ 700 K is reported. Abrupt change in frequency and line width of the external and internal modes have been observed. Analysis of the results suggests lithium positional disorder and sulphate orientational disorder in the high temperature phase (II). The results also throw some light on the existence of twin domains in the crystal.

The interpolation model for molecular reorientation in gases and liquids has been extended to the case for symmetric top molecules. It has been compared with experimental correlation functions for linear as well as prolate and oblate symmetric top molecules. The agreement is excellent for systems where the intermolecular torque is small. With increasing torque, there is discrepancy at short times whereas at intermediate and long times the decay is described quite well. However for liquids at low temperatures, the description of molecular reorientation within the framework of this model is unsatisfactory.