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Updated: Jun 8, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Orientation and mutual location of ions at the surface of ionic liquids
Vera Lockett1, Rossen Sedev, Sarah Harmer
1Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia. Vera.Lockett@gmail.com
Abstract:
The structure of the liquid-vacuum interface in room temperature ionic liquids (ILs) is investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS) and synchrotron X-ray photoelectron spectroscopy (SXPS). By varying the polar angle and comparing the results for the chosen ionic liquids, we identify the presence of a surface layer that is chemically different to the bulk. In particular, this layer: (i) is enriched by aliphatic carbon atoms from the saturated carbon chains of the anions and cations, and (ii) contains an unequal distribution of cations and anions in a direction normal to the surface. This unequal distribution creates a potential gradient which extends from the surface into the liquid. We show unequivocally that this layer is not due to the presence of impurities.
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