We report 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 this ratio (Da/Db) cannot be larger than two, but wall confinement was found to substantially alter diffusion anisotropy and substantially slow particle diffusion along the short axis.
@article{arxiv.0903.1332,
title = {Diffusion of single ellipsoids under quasi-2D confinements},
author = {Y. Han and A. Alsayed and M. Nobili and A. G. Yodh},
journal= {arXiv preprint arXiv:0903.1332},
year = {2009}
}