Translational and Reorientational Dynamics of an Imidazolium-Based Ionic Liquid

Abstract

We present results of parallel quasielastic neutron scattering (QENS) experiments and molecular dynamics numerical simulations for the dynamics of a prototype ionic liquid, 1-ethyl-3-methyl-imidazolium bromide. Differences and similarities with those from the crystal phase are also discussed. Both experiment and simulation demonstrate that, in the length and time scales being probed here (fractions of a nm and a few ps), the dynamics are dominated by activated translational diffusion in the liquid phase and reorientations of the ethyl groups in both solid and liquid.

Microscopic Diffusion Dynamics of Silver Complex‐Based Room‐Temperature Ionic Liquids Probed by Quasielastic Neutron Scattering

“…[21][22][23][24][25][26][27] The faster QENS processes were often attributed to the motions of particular side groups (e.g. ethyl group reorientation in 1-ethyl-3-methyl-imidazolium bromide [26] ). When the faster processes were attributed to the motions of ions as a whole, they were referred to as b relaxation (in QENS terms, the reorientational diffusion component) characterized by negligible Q-dependence.…”

Dynamics of Butyl- and Hexyl-Methylimidazolium Bromide Ionic Liquids

“…3, and the fitted values of D and τ 0 are given in Table I. Comparing the three liquids C 2 mimBr [23], BmimBr and HmimBr, the diffusion constant decreases and residence time increases with increasing alkyl chain length. The broader Lorentzians represents the faster and the localized dynamics.…”

“…However, the number of QENS studies is still relatively small [18][19][20][21][22]. For C 2 mimBr, we have studied the dynamics of both crystal and liquid phases [23]. Figure 1 shows the structure of the C 2 mim+ cation with the possible reorientation motions, denoted by labels 1-4.…”

QENS Study of Diffusive and Localized Cation Motions of Pyridinium-Based Ionic Liquids

“…At the first step it seems to be complicated to include all possible variants into the analytical form of the scattering law, so that we started analyzing experimental data with a model independent approach. As for the similar systems [7][8][9][10] we considered a global process (unrestricted diffusion) and localized dynamics presented by the equations:…”