Laboratory for Neutron Scattering, Paul Scherrer Institut, Villigen-PSI, Switzerland.
J Phys Chem B. 2012 Nov 8;116(44):13265-71. doi: 10.1021/jp3070344. Epub 2012 Oct 26.
Quasielastic neutron scattering (QENS) has been used to study the cation dynamics in the pyridinium based ionic liquid (IL) 1-N-butylpyridinium bis((trifluoromethyl)sulfonyl)imide (BuPy-Tf(2)N). This IL allows for a detailed investigation of the dynamics of the cations only, due to the huge incoherent scattering cross section of the cation (σ(inc)(cation) >> σ(inc)(anion)). The measured spectra can be decomposed into two Lorentzian lines, indicative of two distinct dynamic processes. The slower of these two processes is diffusive in nature, whereas the faster one can be attributed to localized motions. The temperature dependence of the diffusion coefficient of the slow process follows an Arrhenius law, with an activation energy of E(A) = 14.8 ± 0.3 kJ/mol. Furthermore, we present here results from experiments with polarized neutrons. These experiments clearly show that the slower of the two observed processes is coherent, while the faster one is incoherent in nature.
准弹性中子散射（QENS）已被用于研究基于吡啶的离子液体（IL）1-正丁基吡啶双（三氟甲基磺酰基）亚胺（BuPy-Tf(2)N）中阳离子的动力学。由于阳离子的非相干散射截面非常大（σ(inc)(cation) >> σ(inc)(anion)），该 IL 允许仅详细研究阳离子的动力学。测量的光谱可以分解为两个洛伦兹线，表明存在两种不同的动态过程。这两个过程中较慢的一个是扩散性质的，而较快的一个可以归因于局部运动。慢过程的扩散系数随温度的变化遵循阿仑尼乌斯定律，其活化能 E(A) = 14.8 ± 0.3 kJ/mol。此外，我们在此处呈现了带有极化中子的实验结果。这些实验清楚地表明，观察到的两个过程中较慢的一个是相干的，而较快的一个是本质上不相干的。
