Molecular dynamics in Ch 2Cl 2/decalin glass

Abstract

The dielectric loss in a glassy solution of CH 2Cl 2 in decalin has been measured in the kHz and THz frequency ranges at 107–148 K. The low frequency part of the loss curve exhibits a peak which shifts upwards by about two decades with a 4 K increase in temperature, and at the glass to liquid transition temperature moves almost immediately out of the audio frequency range into the microwave. The far infrared peak in the loss is displaced by 30 cm −1 to 90 cm − in the glass as compared with the liquid solution at 293 K. These results are interpreted with a new version of itinerant libration whereby collective reorientations are treated as essential in explaining the complete loss profile in CH 2Cl 2/decalin glass which covers at least twelve decades of frequency. It is argued that in addition to the well documented primary and secondary losses in glasses and polymers, there exists in general a tertiary process at far infrared frequencies analogous to the Poley absorption in liquids. This is part of the dynamical evolution in a wide range of disordered solids.