Open AccessQuasi-two-dimensional diffusion of single ellipsoids: Aspect ratio and confinement effects
Author(s) -
Yilong Han,
Ahmed AlSayed,
Maurizio Nobili,
Arjun G. Yodh
Publication year - 2009
Publication title -
physical review e
Language(s) - English
Resource type - Journals
eISSN - 1550-2376
pISSN - 1539-3755
DOI - 10.1103/physreve.80.011403
Subject(s) - aspect ratio (aeronautics) , ellipsoid , rotational diffusion , diffusion , anisotropy , brownian motion , particle (ecology) , materials science , axial ratio , molecular physics , physics , geometry , optics , mathematics , thermodynamics , composite material , oceanography , astronomy , quantum mechanics , circular polarization , geology , microstrip
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
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