Dynamics of RTILs: a comparative dielectric and OKE study

Sonnleitner, T., Turton, D. A., Waselikowski, S., Hunger, J., Stoppa, A., Walther, M., Wynne, K. and Buchner, R. (2014) Dynamics of RTILs: a comparative dielectric and OKE study. Journal of Molecular Liquids, 192, pp. 19-25. (doi:10.1016/j.molliq.2013.09.019)

[img]
Preview
Text
93249.pdf - Accepted Version

2MB

Abstract

The dynamics of room-temperature ionic liquids (RTILs) were studied by investigating their dielectric relaxation (DR) and time-resolved optical Kerr-effect (OKE) spectra in the frequency range of ~ 10 MHz to ~ 20 THz. For the studied RTILs the OKE and DR spectra are dominated by a relaxation in the GHz region and extend to a relatively sharp band at around 10 THz. Whilst the first feature is mainly associated with the structural relaxation of the fluid through ion rotation (α relaxation), the second indicates the short-time limit of intermolecular dynamics. The rather featureless intermediate region is mainly associated with intermolecular vibrations that are strongly coupled to hindered rotations. In contrast to other RTILs, imidazolium salts show an additional sub-α relaxation which dominates the OKE signal and is indicative of the breathing motion of rather long-lived cages.

Mixed with polar solvents RTILs were found to retain their ionic liquid-like character up to relatively high levels of dilution, but with the overall dynamics considerably speeded up. Below RTIL mole fractions of ~ 0.2–0.4 these systems behave like conventional electrolyte solutions with more or less pronounced ion pairing.

Item Type:Articles
Additional Information:NOTICE: this is the author’s version of a work that was accepted for publication in the Journal of Molecular Liquids. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Molecular Liquids 192:19-25 April 2014 DOI: 10.1016/j.molliq.2013.09.019
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Turton, Dr David and Wynne, Professor Klaas
Authors: Sonnleitner, T., Turton, D. A., Waselikowski, S., Hunger, J., Stoppa, A., Walther, M., Wynne, K., and Buchner, R.
College/School:College of Science and Engineering > School of Chemistry
Research Group:UCP
Journal Name:Journal of Molecular Liquids
Publisher:Elsevier B.V.
ISSN:0167-7322
ISSN (Online):1873-3166
Copyright Holders:Copyright © 2013 Elsevier B.V.
First Published:First published in the Journal of Molecular Liquids 192:19-25
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

University Staff: Request a correction | Enlighten Editors: Update this record

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
559071Two-dimensional terahertz/IR spectroscopy: a unique probe of ultrafast hydrogen-bond dynamics of liquid water and model systems.Klaas WynneEngineering & Physical Sciences Research Council (EPSRC)EP/F06926X/1CHEM - CHEMISTRY
582891The structure and dynamics of water confined in nanoscale pools: the dynamic crossoverKlaas WynneEngineering & Physical Sciences Research Council (EPSRC)EP/J009733/1CHEM - CHEMISTRY