title: Liquid/solid interface of ultrathin ionic liquid films: [C1C1Im][Tf2N] and [C8C1Im][Tf2N] on Au(111).
abstract: Ultrathin films of two imidazolium-based ionic liquids (IL), [C(1)C(1)Im][Tf(2)N] (= 1,3-dimethylimidazolium bis(trifluoromethyl)imide) and [C(8)C(1)Im][Tf(2)N] (= 1-methyl-3-octylimidazolium bis(trifluoromethyl)imide) were prepared on a Au(111) single-crystal surface by physical vapor deposition in ultrahigh vacuum. The adsorption behavior, orientation, and growth were monitored via angle-resolved X-ray photoelectron spectroscopy (ARXPS). Coverage-dependent chemical shifts of the IL-derived core levels indicate that for both ILs the first layer is formed from anions and cations directly in contact with the Au surface in a checkerboard arrangement and that for [C(8)C(1)Im][Tf(2)N] a reorientation of the alkyl chain with increasing coverage is found. For both ILs, geometry models of the first adsorption layer are proposed. For higher coverages, both ILs grow in a layer-by-layer fashion up to thicknesses of at least 9 nm (>10 ML). Moreover, beam damage effects are discussed, which are mainly related to the decomposition of [Tf(2)N](-) anions directly adsorbed at the gold surface.
authors.affiliation: Lehrstuhl für Physikalische Chemie II and Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität, Erlangen-Nürnberg Egerlandstrasse 3, 91058 Erlangen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Cremer
authors.forename: M
authors.initials: M
authors.lastname: Stark
authors.forename: A
authors.initials: A
authors.lastname: Deyko
authors.forename: H-P
authors.initials: HP
authors.lastname: Steinrück
authors.forename: F
authors.initials: F
authors.lastname: Maier