Dedic J, Okur H I, Roke S
Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Sci Adv. 2019 Dec 6;5(12):eaay1443. doi: 10.1126/sciadv.aay1443. eCollection 2019 Dec.
Ions interact with water via short-ranged ion-dipole interactions. Recently, an additional unexpected long-ranged interaction was found: The total electric field of ions influences water-water correlations over tens of hydration shells, leading to the Jones Ray effect, a 0.3% surface tension depression. Here, we report such long-range interactions contributing substantially to both molecular and macroscopic properties. Femtosecond elastic second harmonic scattering (fs-ESHS) shows that long-range electrostatic interactions are remarkably strong in aqueous polyelectrolyte solutions, leading to an increase in water-water correlations. This increase plays a role in the reduced viscosity, which changes more than two orders of magnitude with polyelectrolyte concentration. Using DO instead of HO shifts both the fs-ESHS and the viscosity curve by a factor of ~10 and reduces the maximum viscosity value by 20 to 300%, depending on the polyelectrolyte. These phenomena cannot be explained using a mean-field approximation of the solvent and point to nuclear quantum effects.
离子通过短程离子 - 偶极相互作用与水相互作用。最近，人们发现了另一种意想不到的长程相互作用：离子的总电场会影响数十个水化层上的水 - 水相关性，从而导致琼斯 - 雷效应，即表面张力降低0.3%。在此，我们报告这种长程相互作用对分子和宏观性质都有重大贡献。飞秒弹性二次谐波散射（fs - ESHS）表明，长程静电相互作用在聚电解质水溶液中非常强，导致水 - 水相关性增加。这种增加在降低粘度方面起作用，粘度随聚电解质浓度变化超过两个数量级。用D₂O代替H₂O会使fs - ESHS和粘度曲线都移动约10倍，并根据聚电解质的不同使最大粘度值降低20%至300%。这些现象无法用溶剂的平均场近似来解释，表明存在核量子效应。
