Structural heterogeneity in Ionic Liquids (ILs) is to a large extent defined by nanoscale apolar pockets that act as spacers between strings of positive and negative charges that alternate. In contrast to this, recent work from our group and that of others appear to indicate that dynamic, energetic, and mechanical heterogeneities are governed by the charged part of the liquid. In this article, we study the dynamics of methane, a small apolar solute, in the family of ILs 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (${{\text{Im}}_{1,n}}^{+}$/NTf₂⁻), with n = 2, 4, 8 at temperatures that make the viscosity for each liquid similar and around 8 cP. We do this in an attempt to equalize the effect of the solvent on the dynamics of the solute. In all cases, we find that solute proximity to charge-enhanced regions coincides with translationally caged regimes (high local friction) whereas the opposite is true in charge-depleted regions. In a way, these ILs behave like a liquid within a liquid where the charge network is the high friction component.

中文翻译：

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在离子液体中，高局部摩擦取决于与电荷网络的接近程度

离子液体（ILs）中的结构异质性在很大程度上由纳米级非极性囊袋定义，该囊袋充当交替排列的正负电荷串之间的间隔物。与此相反，我们小组和其他小组的最新工作似乎表明，动态，高能和机械异质性是由液体的带电部分控制的。在本文中，我们研究了ILs 1-烷基-3-甲基咪唑鎓双（三氟甲基磺酰基）酰亚胺（${{\text{我是}}_{\mathrm{1个}，ñ}}^{+}$/ NTf ₂ ⁻），在使每种液体的粘度相似且约为8 cP的温度下，n = 2、4、8。我们这样做是为了平衡溶剂对溶质动力学的影响。在所有情况下，我们都发现，与电荷增强区域的溶质接近度与平移笼形结构（高局部摩擦力）相吻合，而在电荷耗尽的区域则相反。在某种程度上，这些IL的行为就像液体中的液体，其中电荷网络是高摩擦分量。