A Comparative Study on the Electronic Structure of the 1-Ethyl-3-Methylimidazolium Bis(trifluoromethylsulfonyl)amide RT-Ionic Liquid by Electron Spectroscopy and First Principles Calculations

Abstract

The near-surface electronic structure of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide has been investigated with ultraviolet and X-ray photoelectron spectroscopy as well as metastable induced electron spectroscopy. The results have been compared with density functional theory calculations. The good agreement between the experimental and theoretical data provides detailed insight into the origin of the observed spectral features. In particular, we found that a simple composition of the spectra of the isolated ions does not suffice to fit to the experimental results, but interionic interactions have to be considered.

RAIRS Investigations on Films of the Ionic Liquid [EMIM]Tf2N

“…It was verified by MIES and UPS that, as far as the electronic structure of the films prepared on Ag is concerned, their properties are identical with those prepared by similar procedures on Au. 16,19,20 The RAIRS setup contained a Bruker IFS 66v/S vacuum Fourier transform infrared spectrometer, connected directly to a UHV chamber. The Mid-IR beam was coupled to the UHV system through KBr optics, and focussed under an angle of 83.5 degs to the surface normal onto the silver substrate.…”

“…The results were later interpreted by us on the basis of DFT calculations on isolated ion pairs. 19,20 While these studies delivered considerable insight into the structure of the surface-near region at room temperature (RT), the change in the structure of the films during the liquid-toamorphous solid phase transition, which takes place during fast cooling, remained poorly understood.…”

Theoretical reconstruction and elementwise analysis of photoelectron spectra for imidazolium-based ionic liquids

“…an enrichment of one ion may occur). This has been investigated with various UHV techniques, e.g., X-ray photoelectron spectroscopy (XPS), 1,[25][26][27][28][29][30] soft X-ray emission spectroscopy, 31,32 secondary ion mass spectroscopy, 33 scanning atom probe, 34 high resolution Rutherford backscattering spectroscopy (HRBS). 35,36 Detailed information about the surface structure has also been obtained by other surface sensitive methods, e.g.…”

Tunable Wavelength Soft Photoionization of Ionic Liquid Vapors

“…16 Ab initio calculations, used to predict the structure and interactions of ILs, are typically performed on isolated "gas phase" systems. 17,18 It is therefore attractive to study isolated ion-pairs and to examine basic IL decomposition pathways, such as dissociation or ionization. Since ILs are generally perceived as "green solvents", their decomposition pathways can lead to a variety of products that need to be considered in specific applications.…”