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

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.