title: Terahertz and Infrared Spectroscopy of Room-Temperature Imidazolium-Based Ionic Liquids.
abstract: The terahertz- and infrared-frequency vibrational modes of various room-temperature imidazolium-based ionic liquids with molecular anions were examined extensively. We found that the molar-concentration-normalized absorption coefficient spectra in the low-wavenumber range for imidazolium cations with different alkyl-chain lengths were nearly identical for the same anion. Regarding the overall view of a wide range of imidazolium-based ionic liquids, we found that the reduced mass of the combination of an imidazolium-ring cation and the anion and the force constant play significant roles in determining the central frequency of the broad absorption band. In addition to these findings, we also discuss the correlation between the (+)C-H stretching vibrational modes in the 3000-3300 cm(-1) range of the infrared spectra and the intermolecular vibrational band in the low-wavenumber range. Finally, we describe some interesting characteristics of the intermolecular vibrational band observed in a wide range of imidazolium-based ionic liquids.
authors.affiliation: Advanced ICT Research Institute, National Institute of Information and Communications Technology , 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Advanced ICT Research Institute, National Institute of Information and Communications Technology , 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tominari
authors.affiliation: Advanced ICT Research Institute, National Institute of Information and Communications Technology , 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Shukichi
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology , 4-2-1 Nukuikitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Maya
authors.initials: M
authors.lastname: Mizuno