Dinpajooh Mohammadhasan, Intan Nadia N, Duignan Timothy T, Biasin Elisa, Fulton John L, Kathmann Shawn M, Schenter Gregory K, Mundy Christopher J
Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, USA.
Griffith University, Nathan, Queensland 4111, Australia.
J Chem Phys. 2024 Dec 21;161(23). doi: 10.1063/5.0238708.
The phenomenon of underscreening in concentrated electrolyte solutions leads to a larger decay length of the charge-charge correlation than the prediction of Debye-Hückel (DH) theory and has found a resurgence of both theoretical and experimental interest in the chemical physics community. To systematically understand and investigate this phenomenon in electrolytes requires a theory of concentrated electrolytes to describe charge-charge correlations beyond the DH theory. We review the theories of electrolytes that can transition from the DH limit to concentrations where charge correlations dominate, giving rise to underscreening and the associated Kirkwood Transitions (KTs). In this perspective, we provide a conceptual approach to a theoretical formulation of electrolyte solutions that exploits the competition between molecular-informed short-range (SR) and long-range interactions. We demonstrate that all deviations from the DH limit for real electrolyte solutions can be expressed through a single function ΣQ that can be determined both theoretically and numerically. Importantly, ΣQ can be directly related to the details of SR interactions and, therefore, can be used as a tool to understand how differences in representations of interaction can influence collective effects. The precise function form of ΣQ can be inferred through a Gaussian field theory of both the number and charge densities. The resulting formulation is validated by experiment and can accurately describe the collective phenomenon of screening in concentrated bulk electrolytes. Importantly, the Gaussian field theory predictions of the screening lengths appear to be less than ∼1 nm at concentrations above KTs.
在浓电解质溶液中，欠屏蔽现象导致电荷 - 电荷关联的衰减长度比德拜 - 休克尔（DH）理论的预测值更大，并且在化学物理领域引发了理论和实验研究的再度兴起。要系统地理解和研究电解质中的这一现象，需要一种浓电解质理论来描述超出DH理论的电荷 - 电荷关联。我们回顾了能够从DH极限转变到电荷关联占主导地位的浓度的电解质理论，这种转变会导致欠屏蔽以及相关的柯克伍德转变（KTs）。从这个角度出发，我们提供了一种概念性方法，用于对电解质溶液进行理论公式化，该方法利用了分子信息短程（SR）和长程相互作用之间的竞争。我们证明，实际电解质溶液与DH极限的所有偏差都可以通过一个单一函数ΣQ来表示，该函数可以通过理论和数值方法确定。重要的是，ΣQ可以直接与SR相互作用的细节相关联，因此可以用作理解相互作用表示方式的差异如何影响集体效应的工具。ΣQ的精确函数形式可以通过数密度和电荷密度的高斯场理论推导得出。所得公式通过实验得到验证，并且能够准确描述浓体电解质中屏蔽的集体现象。重要的是，在高于KTs的浓度下，高斯场理论预测的屏蔽长度似乎小于约1纳米。
