Han Yilong, Alsayed Ahmed, Nobili Maurizio, Yodh Arjun G
Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Jul;80(1 Pt 1):011403. doi: 10.1103/PhysRevE.80.011403. Epub 2009 Jul 21.
We report on video-microscopy measurements of the translational and rotational Brownian motions of isolated ellipsoidal particles in quasi-two-dimensional sample cells of increasing thickness. The long-time diffusion coefficients were measured along the long (Da) and short (Db) ellipsoid axes, respectively, and the ratio, Da/Db, was determined as a function of wall confinement and particle aspect ratio. In three dimensions (3D), this ratio (Da/Db) cannot be larger than 2, but in quasi-two dimensions, wall confinement was found to substantially alter diffusion anisotropy and substantially slow particle diffusion along the short axis compared to 3D.
我们报告了在厚度不断增加的准二维样品池中对孤立椭球形颗粒的平移和旋转布朗运动进行的视频显微镜测量。分别沿着椭球体的长轴（Da）和短轴（Db）测量了长时间扩散系数，并确定了Da/Db的比值作为壁面限制和颗粒纵横比的函数。在三维（3D）中，该比值（Da/Db）不能大于2，但在准二维中，发现壁面限制会显著改变扩散各向异性，并且与三维相比，会使颗粒沿短轴的扩散显著减慢。
