Share Email Print

Proceedings Paper

Terahertz dynamics of ionic liquids from a combined dielectric relaxation, terahertz, and optical Kerr effect study: evidence for mesoscopic aggregation
Author(s): David A. Turton; Johannes Hunger; Alexander Stoppa; Glenn Hefter; Andreas Thoman; Markus Walther; Richard Buchner; Klaas Wynne
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

To exploit the great potential of room-temperature ionic liquids (RTILs) as solvents that offer both low environmental impact and product selectivity, an understanding of the liquid structure, the microscopic dynamics, and the way in which the pertinent macroscopic properties, such as viscosity, thermal conductivity, ionic diffusion, and solvation dynamics depend on these properties, is essential. We have measured the intermolecular dynamics of the 1,3-dialkylimidazoliumbased RTILs [emim][BF4], [emim][DCA], and [bmim][DCA], at 25 °C from below 1 GHz to 10 THz by ultrafast optical Kerr effect (OKE) spectroscopy and dielectric relaxation spectroscopy (DRS) augmented by time-domain terahertz and far-infrared FTIR spectroscopy. This concerted approach allows a more detailed analysis to be made of the relatively featureless terahertz region, where the higher frequency diffusional modes are strongly overlapped with librations and intermolecular vibrations. In the terahertz region, the signal-to-noise ratio of the OKE spectra is particularly high and the data show that there is a greater number of librational and intermolecular vibrational modes than previously detected. Of greatest interest though, is an intense low frequency (sub-alpha) relaxation that we show is in strong accordance with recent simulations that observe mesoscopic structure arising from aggregates or clusters; structure that explains the anomalous and inconveniently-high viscosities of these liquids.

Paper Details

Date Published: 4 March 2010
PDF: 10 pages
Proc. SPIE 7601, Terahertz Technology and Applications III, 76010H (4 March 2010);
Show Author Affiliations
David A. Turton, Univ. of Strathclyde (United Kingdom)
Johannes Hunger, Univ. of Regensburg (Germany)
Alexander Stoppa, Univ. of Regensburg (Germany)
Glenn Hefter, Murdoch Univ. (Australia)
Andreas Thoman, Albert-Ludwigs-Univ. Freiburg (Germany)
Markus Walther, Albert-Ludwigs-Univ. Freiburg (Germany)
Richard Buchner, Univ. of Regensburg (Germany)
Klaas Wynne, Univ. of Strathclyde (United Kingdom)

Published in SPIE Proceedings Vol. 7601:
Terahertz Technology and Applications III
Laurence P. Sadwick; Creidhe M. M. O'Sullivan, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?