Charged colloidal particles in a charged wedge: do they go in or out?
Charged colloidal particles in a charged wedge: do they go in or out?
复制标题
带电楔中的带电胶体颗粒：它们是进还是出？
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
T. Palberg
中科院分区：
文献类型：
--
作者：
H. Löwen;A. Härtel;A. Barreira;H. Schöpe;E. Allahyarov;T. Palberg
利用真实空间显微镜实验、理论和计算机模拟，我们研究了高带电胶体粒子的行为，这些胶体粒子被限制在两个形成楔形几何形状的高带电平板之间。在低盐条件下，实验观察到胶体颗粒聚集在楔形体的尖端，形成致密的流体或晶体有序结构。这种行为可以在不同的晶胞几何形状、盐浓度和引力强度下发现，甚至在系统中存在附加对流时保持稳定。在线性筛选理论的基础上，对这种影响进行了定性的理解。对于单个宏观离子，线性屏蔽理论预测，在德拜-胡克尔屏蔽长度范围的尖端附近会有一个吸引人的“陷阱”力。随着宏观离子与楔形尖端距离的减小，引力呈对数发散，而在较远的距离上，引力是排斥的。线性屏蔽理论的结果被带有显式共离子和反离子的原始电解液模型的计算机模拟所证实。
Using real-space microscopy experiments, theory and computer simulation, we study the behaviour of highly charged colloidal particles which are confined between two highly charged plates forming a wedge geometry. Under low salt conditions it is experimentally observed that colloidal particles accumulate in the cusp of a wedge to form dense fluid or crystalline ordered structures. This behaviour is found for various cell geometries, salt concentrations and gravitational strengths, and even stays stable when additional convection is present in the system. An effort is made to understand this effect qualitatively on the basis of linear screening theory. For a single macro-ion, linear screening theory predicts an attractive ‘trapping’ force close to the cusp of the range of the Debye–Hückel screening length. The attractive force diverges logarithmically with decreasing distance of the macro-ion from the wedge cusp, while at large distances the force is repulsive. The results of the linear screening theory are confirmed by computer simulations of the primitive electrolyte model with explicit co- and counterions.