Experimental vibrational study of imidazolium-based ionic Liquids: Raman and infrared spectra of 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl) imide and 1-ethyl-3-methylimidazolium ethylsulfate

Experimental vibrational study of imidazolium-based ionic Liquids: Raman and infrared spectra of 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl) imide and 1-ethyl-3-methylimidazolium ethylsulfate
Kiefer, Johannes[1];Fries, Juergen[2];Leipertz, Alfred[1];
[1]Lehrstuhl für Technische Thermodynamik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany[2]AnP/QMM8, Robert Bosch GmbH, D-91522 Ansbach, Germany
Source: Applied Spectroscopy,v 61, n 12,p 1306-1311,December 2007;ISSN: 00037028;DOI: 10.1366/000370207783292000; Publisher: Society for Applied Spectroscopy
Abstract: The vibrational structure of two room-temperature ionic liquids with the cation 1-ethyl-3-methylimidazolium [EMIM] and the respective anions bis(trifluoromethylsulfonyl)imide [TFSI] and ethylsulfate [EtOSO3] is investigated. In particular, attenuated total reflection (ATR) infrared (IR) as well as Raman spectra in the spectral range from 500 to 3500 cm-1 have been recorded and analyzed. Moreover, the depolarization ratios of the Raman lines are determined. The individual peaks are assigned to the corresponding vibrational modes of the molecules. While the CH stretching region around 3000 cm-1 is dominating in Raman spectra, it is remarkably weak in IR spectra. Finally, the results for 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide are compared to previous studies of single ions available in the literature. This comparison shows good agreement. 2007 Society for Applied Spectroscopy.(36 refs)