title: Dielectric and shear relaxations of ionic liquid composed of symmetric ions.
abstract: The frequency-dependent conductivity and shear viscosity of an ionic liquid composed of symmetric ions were determined experimentally in the MHz region. The ionic liquid studied was tetraoctylphosphonium bromide. An isomer with an asymmetric cation, trihexyltetradecylphosphonium bromide, was also investigated to clarify the possible role of the reorientational motion of the cations in the two relaxation spectra. Both the conductivity and the shear viscosity show relaxation in the MHz region, and these relaxation spectra scarcely depend on the asymmetry of the cations. It is, therefore, concluded that the coupling of the reorientational mode of cations with these relaxation spectra is marginal, and that these spectra reflect mainly the frequency-dependent translational motion of ions.
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Furo-cho B2-3 (611), Chikusa, Nagoya, Aichi 464-8603, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Furo-cho B2-3 (611), Chikusa, Nagoya, Aichi 464-8603, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Koda