Issue 28, 2013

Glassy dynamics of sorbitol solutions at terahertz frequencies

Abstract

The absorption spectra of D-sorbitol and a range of its concentrated aqueous solutions were studied by terahertz spectroscopy over the temperature interval of 80 K < T < 310 K. It is shown that the slow-down of molecules at around the glass transition temperature, Tg, dramatically influences the thermal dependence of the absorption at terahertz frequencies. Furthermore, two different absorption regimes are revealed below Tg: at temperatures well below Tg, the absorption resembles the coupling of terahertz radiation to the vibrational density of states (VDOS); above these temperatures, between 160 K and Tg, in the sample of pure sorbitol and the sample of a solution of 70 wt% sorbitol in water, another type of absorption is observed at terahertz frequencies. Several possibilities of the physical origin of this absorption are discussed and based on the experimental data this process is tentatively assigned to the Johari–Goldstein β-relaxation processes shifting to lower frequencies at temperatures below Tg leaving behind a spectrum largely dominated by losses into the VDOS.

Graphical abstract: Glassy dynamics of sorbitol solutions at terahertz frequencies

Article information

Article type
Paper
Submitted
08 May 2013
Accepted
30 May 2013
First published
31 May 2013
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2013,15, 11931-11942

Glassy dynamics of sorbitol solutions at terahertz frequencies

J. Sibik, E. Y. Shalaev and J. Axel Zeitler, Phys. Chem. Chem. Phys., 2013, 15, 11931 DOI: 10.1039/C3CP51936H

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