Composition of the outermost layer and concentration depth profiles of ammonium nitrate ionic liquid surfaces

Christiaan Ridings, Gregory Warr, Gunther Andersson

    Research output: Contribution to journalArticle

    22 Citations (Scopus)

    Abstract

    Differences in the surface structure of protic ionic liquids (ILs) with three different cations and a common anion; ethyl-, propyl- and 2-hydroxyethyl- (or ethanol-) ammonium nitrate (EAN, PAN and EtAN, respectively) have been observed by neutral impact collision ion scattering spectroscopy (NICISS) and metastable induced electron spectroscopy/ultraviolet photoelectron spectroscopy (MIES/UPS). NICISS is used to determine the concentration depth profiles of the elements in each IL and it reveals an enrichment of cation alkyl chains of PAN and EtAN in the outermost layer compared to EAN, and a corresponding depletion of nitrate from the outermost layer of the EtAN surface. MIES probes the molecular orbitals of only the species in the outermost layer of a sample and confirms that, while both the anion and the cation are present to some degree at the surface of all three ILs, the cation is enriched to a greater extent at the surface of PAN and EtAN compared to EAN.

    Original languageEnglish
    Pages (from-to)16088-16095
    Number of pages8
    JournalPhysical Chemistry Chemical Physics
    Volume14
    Issue number46
    DOIs
    Publication statusPublished - 14 Dec 2012

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