title: Interactions and dynamics in ionic liquids.
abstract: Precise dielectric spectra have been determined at 25 degrees C over the exceptionally broad frequency range of 0.1 <or= nu/GHz <or= 3000 for the imidazolium-based room-temperature ionic liquids (RTILs) [bmim][BF4], [bmim][PF6], [bmim][DCA], and [hmim][BF4]. The spectra are dominated by a low-frequency process at approximately 1 GHz with a broad relaxation time distribution of the Cole-Davidson or Cole-Cole type, which is thought to correspond to the rotational diffusion of the dipolar cations. In addition, these RTILs possess two Debye relaxations at approximately 5 GHz and approximately 0.6 THz and a damped harmonic oscillation at approximately 2.5 THz. The two higher-frequency modes are almost certainly due to cation librations, but the origin of the approximately 5 GHz mode remains obscure.
authors: Institut für Physikalische und Theoretische Chemie, Universität Regensburg, D-93040 Regensburg, Germany.
authors: Alexander
authors: A
authors: Stoppa
authors: Johannes
authors: J
authors: Hunger
authors: Richard
authors: R
authors: Buchner
authors: Glenn
authors: G
authors: Hefter
authors: Andreas
authors: A
authors: Thoman
authors: Hanspeter
authors: H
authors: Helm