Orientation and mutual location of ions at the surface of ionic liquids

Vera Lockett, Rossen Sedev, Sarah Harmer-Bassell, John Ralston, Mike Horne, Theo Rodopoulos

    Research output: Contribution to journalArticlepeer-review

    78 Citations (Scopus)


    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.

    Original languageEnglish
    Pages (from-to)13816-13827
    Number of pages12
    JournalPhysical Chemistry Chemical Physics
    Issue number41
    Publication statusPublished - 7 Nov 2010


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