Luo Peng, Zhai Yanqin, Senses Erkan, Mamontov Eugene, Xu Guangyong, Z Y, Faraone Antonio
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
J Phys Chem Lett. 2020 Nov 5;11(21):8970-8975. doi: 10.1021/acs.jpclett.0c02619. Epub 2020 Oct 8.
The structural relaxation in water solutions of kosmotrope (structure maker) and chaotrope (structure breaker) salts, namely sodium chloride, potassium chloride, and cesium chloride, were studied through quasielastic neutron scattering measurements. We found that the collective dynamics relaxation time at the structure factor peak obtained using heavy water solutions shows a distinctively different behavior in the kosmotrope as opposed to the chaotrope solutions, increasing with the salt concentration in the former and decreasing in the latter. In both cases the trends are proportional to the concentration dependence of the relative viscosity of the solutions. These results indicate that kosmotropes and chaotropes influence the solution's viscosity by impacting in opposite ways the hydrogen bond network of water, strengthening it in one case and softening it in the other.
通过准弹性中子散射测量研究了促结构剂（结构形成剂）和促熔剂（结构破坏剂）盐（即氯化钠、氯化钾和氯化铯）在水溶液中的结构弛豫。我们发现，使用重水溶液在结构因子峰值处获得的集体动力学弛豫时间在促结构剂溶液与促熔剂溶液中表现出明显不同的行为，前者随盐浓度增加，后者随盐浓度降低。在这两种情况下，趋势都与溶液相对粘度的浓度依赖性成正比。这些结果表明，促结构剂和促熔剂以相反的方式影响水的氢键网络，从而影响溶液的粘度，一种情况是增强氢键网络，另一种情况是使其软化。
