Dynamics of imidazolium ionic liquids from a combined dielectric relaxation and optical kerr effect study: evidence for mesoscopic aggregation

Turton, D.A., Hunger, J., Stoppa, A., Hefter, G., Thoman, A., Walther, M., Buchner, R. and Wynne, K. (2009) Dynamics of imidazolium ionic liquids from a combined dielectric relaxation and optical kerr effect study: evidence for mesoscopic aggregation. Journal of the American Chemical Society, 131(31), pp. 11140-11146. (doi:10.1021/ja903315v)

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Abstract

We have measured the intermolecular dynamics of the 1,3-dialkylimidazolium-based room-temperature ionic liquids (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. Of greatest interest though, is an intense low frequency (sub-α) relaxation that we show is in accordance with recent simulations that have reported mesoscopic structure arising from aggregates or clusters—structure that explains the anomalous and inconveniently high viscosities of these liquids.

Item Type:Articles
Additional Information:Reprinted with permission from the Journal of the American Chemical Society 131(31):11140-11146. Copyright (2009) American Chemical Society
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wynne, Professor Klaas
Authors: Turton, D.A., Hunger, J., Stoppa, A., Hefter, G., Thoman, A., Walther, M., Buchner, R., and Wynne, K.
Subjects:Q Science > QD Chemistry
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of the American Chemical Society
Publisher:American Chemical Society
ISSN:0002-7863
ISSN (Online):1520-5126
Published Online:13 July 2009
Copyright Holders:Copyright © 2009 American Chemical Society
First Published:First published in Journal of the American Chemical Society 131(31):11140-11146
Publisher Policy:Reproduced with the permission of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
563561Terahertz spectroscopy of aqueous ionic solutions to understand the role of hydrogen-bond network breaking and strengthening in the HofmeisterKlaas WynneEngineering & Physical Sciences Research Council (EPSRC)EP/E046541/1CHEM - CHEMISTRY