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Length-scales of dynamic heterogeneity in a driven binary colloid.
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2020-08-03 , DOI: 10.1039/d0cp02703k
Suman Dutta 1 , J Chakrabarti
Affiliation  

Here we study the characteristic length scales in an aqueous suspension of a symmetric oppositely charged colloid subjected to a uniform electric field by Brownian dynamics simulations. We consider the in-plane structure in the presence of a sufficiently strong electric field where the like charges in the system form macroscopic lanes. We construct spatial correlation functions characterizing the structural order and that of particles of different mobilities in the plane transverse to the electric field at a given time. We call these functions equal time density correlation functions (ETDCFs). The ETDCFs between particles of different charges, irrespective of mobilities, are the structural ETDCFs, while those between particles of different mobilities are the dynamic ETDCFs. We extract the characteristic length of correlation by fitting the envelopes of the ETDCFs to exponential dependences. We find that the correlation length scales of the structural ETDCFs and the dynamic ETDCFs of the slow particles increase with time in a concurrent manner. This suggests that the clustering of particles tends to build up dynamically correlated slow particles in the plane transverse to the lanes. The ETDCFs can be measured for colloidal systems by directly following the particle motion by video-microscopy and may be useful to understand the patterns out of equilibrium.

中文翻译:

驱动二元胶体中动态异质性的长度尺度。

在这里,我们通过布朗动力学模拟研究了在均匀电场作用下的对称带相反电荷的胶体的水悬浮液中的特征长度尺度。我们考虑在存在足够强电场的情况下的平面内结构,其中系统中的类似电荷形成宏观通道。我们构造了空间相关函数,该函数描述了在给定时间横向于电场的平面中的结构顺序和不同迁移率的粒子的顺序。我们称这些函数为时间密度相关函数(ETDCF)。不论迁移率如何,具有不同电荷的粒子之间的ETDCF都是结构ETDCF,而迁移率不同的粒子之间的ETDCF是动态ETDCF。我们通过使ETDCF的包络适合指数相关性来提取相关的特征长度。我们发现,慢速粒子的结构ETDCF和动态ETDCF的相关长度尺度以并发方式随时间增加。这表明粒子的聚集趋于在横向于车道的平面中建立动态相关的慢粒子。可以通过视频显微镜直接跟踪粒子运动来测量胶体系统的ETDCF,对于理解不平衡的模式可能很有用。这表明粒子的聚集趋于在横向于车道的平面上建立动态相关的慢粒子。可以通过视频显微镜直接跟踪粒子运动来测量胶体系统的ETDCF,对于理解不平衡的模式可能很有用。这表明粒子的聚集趋于在横向于车道的平面上建立动态相关的慢粒子。可以通过视频显微镜直接跟踪粒子运动来测量胶体系统的ETDCF,对于理解不平衡的模式可能很有用。
更新日期:2020-08-18
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