Differential Dynamic Microscopy for Anisotropic Colloidal Dynamics
Differential Dynamic Microscopy for Anisotropic Colloidal Dynamics
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DOI：
10.1021/la204904a
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发表时间：
2012-03-13
期刊：
影响因子：
3.9
通讯作者：
Poon, Wilson C. K.
中科院分区：
文献类型：
--
作者：
Reufer, Mathias;Martinez, Vincent A.;Poon, Wilson C. K.
差分动态显微镜（DDM）是最近发展起来的一种低成本、高通量的技术，用于用白光光学显微镜来表征球形胶体的各向同性扩散。(1)我们发展了应用DDM来探测各向异性胶体样品（如各种有序相或粒子与外场相互作用）动力学的理论。在像平面的任何方向上都可以测量与q相关的动力学。我们在磁场中排列的各向异性磁性颗粒（赤铁矿）的稀水分散体上演示了该方法。平行于场方向和垂直于场方向的扩散系数与理论值吻合较好。我们展示了这些测量如何使我们能够提取系统的方向顺序参数S-2。
Differential dynamic microscopy (DDM) is a low-cost, high-throughput technique recently developed for characterizing the isotropic diffusion of spherical colloids using white-light optical microscopy.(1) We develop the theory for applying DDM to probe the dynamics of anisotropic colloidal samples such as various ordered phases, or particles interacting with an external field. The q-dependent dynamics can be measured in any direction in the image plane. We demonstrate the method on a dilute aqueous dispersion of anisotropic magnetic particles (hematite) aligned in a magnetic field. The measured diffusion coefficients parallel and perpendicular to the field direction are in good agreement with theoretical values. We show how these measurements allow us to extract the orientational order parameter S-2 of the system.