Holographic characterization and tracking of colloidal dimers in the effective-sphere approximation,Soft Matter

当前位置： X-MOL 学术 › Soft Matter › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Holographic characterization and tracking of colloidal dimers in the effective-sphere approximation
Soft Matter ( IF 2.9 ) Pub Date : 2021-2-15 , DOI: 10.1039/d0sm02262d
Lauren E. Altman _{1,

2,

3,

4} , Rushna Quddus _{2,

3,

4,

5} , Fook Chiong Cheong _{3,

4,

6,

7} , David G. Grier _{1,

2,

3,

4}

Affiliation

An in-line hologram of a colloidal sphere can be analyzed with the Lorenz–Mie theory of light scattering to measure the sphere's three-dimensional position with nanometer-scale precision while also measuring its diameter and refractive index with part-per-thousand precision. Applying the same technique to aspherical or inhomogeneous particles yields measurements of the position, diameter and refractive index of an effective sphere that represents an average over the particle's geometry and composition. This effective-sphere interpretation has been applied successfully to porous, dimpled and coated spheres, as well as to fractal clusters of nanoparticles, all of whose inhomogeneities appear on length scales smaller than the wavelength of light. Here, we combine numerical and experimental studies to investigate effective-sphere characterization of symmetric dimers of micrometer-scale spheres, a class of aspherical objects that appear commonly in real-world dispersions. Our studies demonstrate that the effective-sphere interpretation usefully distinguishes small colloidal clusters in holographic characterization studies of monodisperse colloidal spheres. The effective-sphere estimate for a dimer's axial position closely follows the ground truth for its center of mass. Trends in the effective-sphere diameter and refractive index, furthermore, can be used to measure a dimer's three-dimensional orientation. When applied to colloidal dimers transported in a Poiseuille flow, the estimated orientation distribution is consistent with expectations for Brownian particles undergoing Jeffery orbits.

中文翻译：

有效球面近似中的胶体二聚体的全息表征和跟踪

可以使用Lorenz-Mie光散射理论分析胶体球的线内全息图，以纳米级精度测量球体的三维位置，同时以千分之一精度测量球体的直径和折射率。将相同的技术应用于非球面或不均匀的粒子，可以得到有效球体的位置，直径和折射率的测量值，该值代表整个粒子几何形状和组成的平均值。这种有效的球体解释已成功应用于多孔，凹坑和涂层球体，以及纳米颗粒的分形簇，所有这些颗粒的不均匀性均出现在小于光波长的长度尺度上。这里，我们结合数值和实验研究来研究微米级球体的对称二聚体的有效球体表征，微米级球体是在现实世界中的色散中普遍出现的一类非球面物体。我们的研究表明，在单分散胶体球的全息表征研究中，有效球体的解释可有效区分小胶体团簇。二聚体轴向位置的有效范围估计值紧随其质心的地面真实情况。此外，有效球直径和折射率的趋势可用于测量二聚体的三维取向。当应用于以Poiseuille流运输的胶体二聚体时，

更新日期：2021-02-25

点击分享查看原文

点击收藏

公开下载

阅读更多本刊最新论文本刊介绍/投稿指南11