|Title||Dynamics of Liquid 1-Ethyl-3-Methylimidazolium Acetate Measured with Implanted-Ion 8Li β-NMR|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||Fujimoto, D, McFadden, RML, Dehn, MH, Petel, Y, Chatzichristos, A, Hemmingsen, L, Karner, VL, Kiefl, RF, Levy, CDPhilip, McKenzie, I, Michal, CA, Morris, GD, Pearson, MR, Szunyogh, D, Ticknor, JO, Stachura, M, W. MacFarlane, A|
|Journal||Chemistry of Materials|
We demonstrate the application of implanted-ion β-detected NMR as a probe of ionic liquid molecular dynamics through the measurement of 8Li spin-lattice relaxation (SLR) and resonance in 1-ethyl-3-methylimidazolium acetate. The motional narrowing of the resonance and the local maxima in the SLR rate, 1/T1, imply sensitivity to subnanosecond Li+ solvation dynamics. From an analysis of 1/T1, we extract an activation energy EA = 74.8(1.5) meV and Vogel–Fulcher–Tammann constant TVFT = 165.8(0.9) K, in agreement with the dynamic viscosity of the bulk solvent. Near the melting point, the lineshape is broad and intense, and the form of the relaxation is nonexponential, reflective of our sensitivity to heterogeneous dynamics near the glass transition. The depth resolution of this technique may later provide a unique means of studying nanoscale phenomena in ionic liquids.