Groves Timothy S, Perkin Susan
Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK.
Faraday Discuss. 2024 Oct 25;253(0):193-211. doi: 10.1039/d4fd00040d.
Experimental measurements of interactions in ionic liquids and concentrated electrolytes over the past decade or so have revealed simultaneous monotonic and oscillatory decay modes. These observations have been hard to interpret using classical theories, which typically allow for just one electrostatic decay mode in electrolytes. Meanwhile, substantial progress in the theoretical description of dielectric response and ion correlations in electrolytes has illuminated the deep connection between density and charge correlations and the multiplicity of decay modes characterising a liquid electrolyte. The challenge in front of us is to build connections between the theoretical expressions for a pair of correlation functions and the directly measured free energy of interaction between macroscopic surfaces in experiments. Towards this aim, we here present measurements and analysis of the interactions between macroscopic bodies across a fluid mixture of two ionic liquids of widely diverging ionic size. The measured oscillatory interaction forces in the liquid mixtures are significantly more complex than for either of the pure ionic liquids, but can be fitted to a superposition of two oscillatory and one monotonic mode with parameters matching those of the pure liquids. We discuss this empirical finding, which hints at a kind of wave mechanics for interactions in liquid matter.
在过去十年左右的时间里，对离子液体和浓电解质中相互作用的实验测量揭示了同时存在的单调衰减和振荡衰减模式。使用经典理论很难解释这些观测结果，因为经典理论通常只允许电解质中存在一种静电衰减模式。与此同时，电解质中介电响应和离子相关性的理论描述取得了重大进展，揭示了密度和电荷相关性之间的深层联系以及表征液体电解质的衰减模式的多样性。我们面临的挑战是在一对相关函数的理论表达式与实验中直接测量的宏观表面之间的相互作用自由能之间建立联系。为了实现这一目标，我们在此展示了对跨越两种离子大小差异很大的离子液体的流体混合物中宏观物体之间相互作用的测量和分析。在液体混合物中测量到的振荡相互作用力比任何一种纯离子液体都要复杂得多，但可以拟合为两种振荡模式和一种单调模式的叠加，其参数与纯液体的参数相匹配。我们讨论了这一经验发现，它暗示了液体物质中相互作用的一种波动力学。
