This research project will make use of Brillouin and Raman scattering to investigate the incommensurate and lock-in phase transitions in several dielectric crystals. The specific projects include: 1) studies of the longitudinal acoustic anomalies in potassium selenate near the characteristic temperature TI and controversial asymmetries in transverse acoustic modes in potassium selenate and tetramethyltetrachlorozincate; 2) clearing up the remaining controversy concerning the dielectric anomaly in thiourea with Brillouin scattering; 3) studies of the glass transition with lithium chloride solutions and other glass-forming materials; 4) a new study of surface acoustic modes of crystals near the melting point in order to search for the onset of surface melting.
