Surface structure of a "non-amphiphilic" protic ionic liquid

Deborah Wakeham, Petru Niga, Christiaan Ridings, Gunther Andersson, Andrew Nelson, Gregory Warr, Steven Baldelli, Mark Rutland, Rob Atkin

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)


    The nanostructure of the ethanolammonium nitrate (EtAN)-air surface has been investigated using X-ray reflectometry (XRR), vibrational sum frequency spectroscopy (VSFS) and neutral impact collision ion scattering spectroscopy (NICISS). The XRR data decays more rapidly than expected for a perfectly sharp interface, indicating a diffuse electron (scattering length) density profile. Modelling of the XRR data using three different fitting routines produced consistent interfacial profiles that suggest the formation of interfacial EtAN clusters. Consistent with this, VSFS reveals that the EtAN surface is predominantly covered by -CH 2- moieties, with the -NH 3 + and -OH groups of the cation buried slightly deeper in the interface. The elemental profiles determined using NICISS also show enrichment of carbon relative to nitrogen and oxygen in the outermost surface layer, which is consistent with the surface cation orientation deduced from VSFS, and with the presence of EtAN aggregates at the liquid surface.

    Original languageEnglish
    Pages (from-to)5106-5114
    Number of pages9
    JournalPhysical Chemistry Chemical Physics
    Issue number15
    Publication statusPublished - 21 Apr 2012


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