Broadband Dielectric Spectroscopy on Glass-Forming Propylene Carbonate

TL;DR

This study employs broadband dielectric spectroscopy to analyze the dielectric response of propylene carbonate across a wide frequency range, revealing detailed insights into alpha-process dynamics, excess wing phenomena, and high-frequency responses in glass-forming liquids.

Contribution

It provides comprehensive broadband dielectric data on propylene carbonate, highlighting differences in high-frequency spectral forms and comparing results with light scattering and theoretical models.

Findings

Alpha-process observed over 14 decades of frequency.

Identification of excess wing at high frequencies.

Differences in spectral form at high frequencies compared to other glass formers.

Abstract

Dielectric spectroscopy covering more than 18 decades of frequency has been performed on propylene carbonate in its liquid and supercooled-liquid state. Using quasi-optic submillimeter and far-infrared spectroscopy the dielectric response was investigated up to frequencies well into the microscopic regime. We discuss the alpha-process whose characteristic timescale is observed over 14 decades of frequency and the excess wing showing up at frequencies some three decades above the peak frequency. Special attention is given to the high-frequency response of the dielectric loss in the crossover regime between alpha-peak and boson-peak. Similar to our previous results in other glass forming materials we find evidence for additional processes in the crossover regime. However, significant differences concerning the spectral form at high frequencies are found. We compare our results to the susceptibilities obtained from light scattering and to the predictions of various models of the glass transition.