Dielectric spectroscopy in benzophenone: The beta relaxation and its relation to the mode-coupling Cole-Cole peak

TL;DR

This study uses broadband dielectric spectroscopy to analyze the glassy dynamics of benzophenone, focusing on the beta relaxation and its potential relation to the mode-coupling Cole-Cole peak, revealing they are likely unrelated.

Contribution

It provides a detailed experimental characterization of benzophenone's dielectric spectra and investigates the possible connection between beta relaxation and the Cole-Cole peak within mode-coupling theory.

Findings

Beta relaxation develops into an excess wing with temperature increase.

The high-frequency Cole-Cole peak does not appear to be directly related to the Johari-Goldstein beta relaxation.

Spectral features observed are not explained by current mode-coupling theory.

Abstract

We report a thorough characterization of the glassy dynamics of benzophenone by broadband dielectric spectroscopy. We detect a well pronounced beta relaxation peak developing into an excess wing with increasing temperature. A previous analysis of results from Optical-Kerr-effect measurements on this material within the mode coupling theory revealed a high-frequency Cole-Cole peak. We address the question if this phenomenon also may explain the Johari-Goldstein beta relaxation, a so far unexplained spectral feature inherent to glass-forming matter, mainly observed in dielectric spectra. Our results demonstrate that according to the present status of theory, both spectral features seem not to be directly related.