Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 3: Ionic Liquids
CPP 3.7: Vortrag
Montag, 31. März 2014, 11:30–11:45, ZEU 260
Electrospray ionization deposition of ultrathin ionic liquid films: [C8C1Im]Cl and [C8C1Im][Tf2N] on Au(111) — •Florian Rietzler, Marius Piermaier, Alexey Deyko, Hans-Peter Steinrück, and Florian Maier — Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen
We introduce a new method for preparing ultrathin ionic liquid (IL) films on surfaces by means of electrospray ionization deposition (ESID) under well defined ultra-high vacuum (UHV) conditions. In contrast to physical vapor deposition (PVD), ESID even allows the deposition of ILs, which are prone to thermal decomposition. We first investigated ultrathin [C8C1Im][Tf2N] (=1-methyl-3-octyl-imidazolium bis(trifluoromethyl)imide) and [C8C1Im]Cl ESID-films on Au(111); [C8C1Im]Cl is an example of an IL that cannot be prepared as ultrathin film otherwise. [C8C1Im][Tf2N] and [C8C1Im]Cl both form a wetting layer with a checkerboard arrangement with the cationic imidazolium ring and the anion adsorbed next to each other on the substrate and the alkyl chain pointing towards vacuum. Further deposition of [C8C1Im]Cl leads to a pronounced island growth on top of the wetting layer, which is independently confirmed by angle-resolved XPS and atomic force microscopy. This behavior contrasts the growth behavior found for [C8C1Im][Tf2N], where layer-by-layer growth on top of the wetting layer is observed. The dramatic difference between both ILs is attributed to differences in the cation-anion interactions, and in the degree of order in the wetting layer of the two ILs.