Slattery, John Martin orcid.org/0000-0001-6491-8302, Smoll, Eric J., Tesa-Serrate, Maria A. et al. (6 more authors) (2017) Determining the Composition of the Vacuum-Liquid Interface in Ionic-Liquid Mixtures. FARADAY DISCUSSIONS. ISSN 1364-5498
Abstract
The vacuum-liquid interfaces of a number of ionic-liquid mixtures have been investigated using a combination of reactive-atom scattering with laser-induced fluorescence detection (RAS-LIF), selected surface tension measurements, and molecular dynamics (MD) simulations. The mixtures are based on the widespread 1-alkyl-3-methylimidazolium ([Cnmim]+) cation, including mixed cations which differ in chain length or chemical functionality with a common anion; and different anions for a common cation. RAS-LIF results imply that the surface compositions exhibit a general form of non-stoichiometric behaviour that mimics the well-known Henry’s and Raoult’s laws at low and high mole fraction, respectively. The Extended Langmuir model provides a moderately good single-parameter fit, but higher-order terms are required for an accurate description. The quantitative relationship between RAS-LIF and surface tension, which probes the surface composition only indirectly, is explored for mixtures of [C2mim]+ and [C12mim]+ with a common bis(trifluoromethylsulfonyl)imide ([NTf2]-) anion. Extended Langmuir model fits to surface tension data are broadly consistent with those to RAS-LIF; however, several other common approaches to extracting surface compositions from measured surface tensions result in much larger discrepancies. MD simulations suggest that RAS-LIF faithfully reports on the alkyl-chain exposure at the surface, which is only subtly modified by composition-dependent structural reorganisation.
Metadata
Item Type: | Article | ||||
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry 2017. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details | ||||
Dates: |
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Institution: | The University of York | ||||
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) | ||||
Funding Information: |
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Depositing User: | Pure (York) | ||||
Date Deposited: | 27 Jun 2017 08:45 | ||||
Last Modified: | 21 Mar 2024 23:29 | ||||
Published Version: | https://doi.org/10.1039/C7FD00175D | ||||
Status: | Published | ||||
Refereed: | Yes | ||||
Identification Number: | https://doi.org/10.1039/C7FD00175D |