2007/12/31 by P. Lunkenheimer, Luis Carlos Pardo, L. C. Pardo +3 · 2 citations
Chemical Engineering · Chemistry · Materials Science · Physics and Astronomy · #Material Dynamics and Properties #Photochemistry and Electron Transfer Studies #Thermodynamic properties of mixtures #cond-mat.dis-nn #cond-mat.soft
paper · pdf · doi:10.1103/physreve.77.031506
published as Phys. Rev. E 77, 031506 (2008) · 11 pages, 7 figures; revised version with new Fig. 5 and some smaller changes according to referees' demands
arxiv created 2008/02/08 · openalex publication_date 2008/03/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We have performed a detailed dielectric investigation of the relaxational dynamics of glass-forming benzophenone. Our measurements cover a broad frequency range of 0.1\phantom\rule0.3em0exHz\phantom\rule0.3em0exto\phantom\rule0.3em0ex120\phantom\rule0.3em0exGHz and temperatures from far below the glass temperature well up into the region of the small-viscosity liquid. With respect to the \ensuremathα relaxation this material can be characterized as a typical molecular glass former with rather high fragility. A good agreement of the \ensuremathα relaxation behavior with the predictions of the mode coupling theory of the glass transition is stated. In addition, at temperatures below and in the vicinity of Tg we detect a well-pronounced \ensuremathβ relaxation of Johari-Goldstein type, which with increasing temperature develops into an excess wing. We compare our results to literature data from optical Kerr effect and depolarized light scattering experiments, where an excess-wing-like feature was observed in the 1--100\phantom\rule0.3em0exGHz region. We address the question if the Cole-Cole peak, which was invoked to describe the optical Kerr effect data within the framework of the mode coupling theory, has any relation to the canonical \ensuremathβ relaxation detected by dielectric spectroscopy.