Abstract We study the aggregation of charged ellipsoidal colloidal particles at the air/water interface. The particles diffuse on the interface and aggregate over time to form fractal structures. We found that the directionality of the interactions depends on the aspect ratio of the particles. For the smaller aspect ratio, the interaction is stronger along the long axis of the particles, as we observe that the particles tend to aggregate side-by-side along this axis. As the aspect ratio increases, the particles arrange themselves mostly tip-to-tip. Using Monte Carlo simulations we built a simple orientation-dependent potential model for each aspect ratio, in such a way that the resulting structures reproduce the main features of the experimental systems. We also found that the larger aspect ratio ellipsoids require fewer particles to reach a constant fractal dimension. In addition, we measured the fractal dimension of clusters for different aspect ratios and found that it depends on the aspect ratio of the particles in the cluster, contrary to the idea that the fractal dimension is universal and therefore does not depend on the shape of the particles. Our results indicate that the fractal dimension decreases as the aspect ratio increases.

中文翻译：

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在空气/水界面由椭球胶体粒子形成的分形聚集体

摘要 我们研究了带电椭球胶体粒子在空气/水界面的聚集。粒子在界面上扩散并随着时间的推移聚集形成分形结构。我们发现相互作用的方向性取决于粒子的纵横比。对于较小的纵横比，沿颗粒长轴的相互作用更强，因为我们观察到颗粒倾向于沿该轴并排聚集。随着纵横比的增加，粒子本身大多以尖端到尖端排列。使用蒙特卡罗模拟，我们为每个纵横比建立了一个简单的依赖于方向的潜在模型，从而使所得结构再现了实验系统的主要特征。我们还发现，较大的长宽比椭球需要较少的粒子来达到恒定的分形维数。此外，我们测量了不同纵横比的簇的分形维数，发现它取决于簇中粒子的纵横比，这与分形维数是通用的因此不依赖于簇的形状的想法相反。粒子。我们的结果表明分形维数随着纵横比的增加而减少。