Physikalische Chemie I, Universität Bayreuth, Germany.
ACS Nano. 2009 Oct 27;3(10):3326-34. doi: 10.1021/nn900902b.
We report on the translation and rotation of particle clusters made through the combination of spherical building blocks. These clusters present ideal model systems to study the motion of objects with complex shape. Since they could be separated into fractions of well-defined configurations on a sufficient scale and because their overall dimensions were below 300 nm, the translational and rotational diffusion coefficients of particle doublets, triplets, and tetrahedrons could be determined by a combination of polarized dynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS). The use of colloidal clusters for DDLS experiments overcomes the limitation of earlier experiments on the diffusion of complex objects near surfaces because the true 3D diffusion can be studied. When the exact geometry of the complex assemblies is known, different hydrodynamic models for calculating the diffusion coefficients for objects with complex shapes could be applied. Because hydrodynamic friction must be restricted to the cluster surface, the so-called shell model, in which the surface is represented as a shell of small friction elements, was most suitable to describe the dynamics. A quantitative comparison of the predictions from theoretical modeling with the results obtained by DDLS showed an excellent agreement between experiment and theory.
我们报告了通过组合球形构建块实现的粒子簇的平移和旋转。这些簇为研究具有复杂形状的物体的运动提供了理想的模型系统。由于它们可以在足够大的尺度上分离成具有明确定义构型的分数，并且由于它们的整体尺寸低于 300nm，因此可以通过偏振动态光散射（DLS）和非偏振动态光散射（DDLS）的组合来确定粒子对、三体和四面体的平移和旋转扩散系数。使用胶体簇进行 DDLS 实验克服了早期在表面附近研究复杂物体扩散的实验的局限性，因为可以研究真正的 3D 扩散。当复杂组装体的精确几何形状已知时，可以应用不同的流体力学模型来计算具有复杂形状的物体的扩散系数。由于必须将流体动力摩擦限制在簇表面上，因此最适合描述动力学的是所谓的壳模型，其中表面表示为具有小摩擦元素的壳。理论建模的预测与通过 DDLS 获得的结果的定量比较表明，实验和理论之间具有极好的一致性。
