论文标题
关于电气充电和电荷反转的性质
On the nature of overcharging and charge inversion in electrical double layers
论文作者
论文摘要
了解过度充电和充电反转是软物质和生物物理学中长期存在的挑战之一。为了研究这些现象，我们采用了经过修改的高斯重新归一化波动理论，该理论允许对空间变化的离子强度以及介电介电效率和排除体积效应的空间变化进行自一致的核算。过度充电对静电耦合的潜在依赖性通过不同的表面电荷，反取价和介电对比度阐明。与模拟一致，确定了与弱，中度和强耦合相对应的三个特征状态。重要特征诸如Zeta电位的反转，表面上的拥挤和离子分层的成功捕获。对于弱耦合，没有过多的收费。在中等耦合方面，过度充电会随表面电荷增加。最后，在强耦合方面，观察到过度充电中的离子拥挤和饱和度。我们的理论预测电荷反转对多价盐浓度的非单调依赖性以及与实验的定量一致性。
Understanding overcharging and charge inversion is one of the long-standing challenges in soft matter and biophysics. To study these phenomena, we employ the modified Gaussian renormalized fluctuation theory, which allows for the self-consistent accounting of spatially varying ionic strength, as well as the spatial variations in dielectric permittivity and excluded volume effects. The underlying dependence of overcharging on the electrostatic coupling is elucidated by varying surface charge, counterion valency, and dielectric contrast. Consistent with simulations, three characteristic regimes corresponding to weak, moderate, and strong coupling are identified. Important features like the inversion of zeta potential, crowding and ionic layering at the surface are successfully captured. For weak coupling, there is no overcharging. In the moderate coupling regime, overcharging increases with surface charge. Finally, in the strong coupling regime, ionic crowding and saturation in overcharging are observed. Our theory predicts non-monotonic dependence of charge inversion on multivalent salt concentration as well as the addition of monovalent salt, in quantitative agreement with experiments.
