1 research outputs found
Surface Analysis of Ionic Liquids with and without Lithium Salt Using X‑ray Photoelectron Spectroscopy
X-ray photoelectron spectroscopy (XPS) was applied to
a neat ionic
liquid 1-ethyl-3-methylimidazolium bisÂ(trifluoromethanesulfonyl)Âimide
[EMI<sup>+</sup>]Â[Tf<sub>2</sub>N<sup>–</sup>] and its lithium
salt solution at room temperature to clarify the composition and structure
of its near-surface region. Core level peaks were recorded for Li
1s, N 1s, C 1s, F 1s, O 1s, S 2s, and S 2p. Valence band XPS spectra
(0–40 eV binding energy) were also studied. The XPS spectra
were analyzed using DV-Xα calculations. Results show that the
planar type isomer of the EMI<sup>+</sup> cation is dominant at the
near-surface region of EMI-Tf<sub>2</sub>N. Results of XPS measurements
show a spectrum of Li 1s in Li/EMI-Tf<sub>2</sub>N. The proposed models
for the preferred orientation of the ions exhibit good agreement with
results obtained from the DV-Xα calculations