Correlated diffusion of colloidal particles near a liquid-liquid interface.
Optical microscopy and multi-particle tracking are used to investigate the cross-correlated diffusion of quasi two-dimensional colloidal particles near an oil-water interface. The behaviors of the correlated diffusion along longitudinal and transverse direction are asymmetric. It is shown that the characteristic length for longitudinal and transverse correlated diffusion are particle diameter d and the distance z from particle center to the interface, respectively, for large particle separation z. The longitudinal and transverse correlated diffusion coefficient D||(r) and D[perpendicular](r) are independent of the colloidal area fraction n when n < 0.3, which indicates that the hydrodynamic interactions(HIs) among the particles are dominated by HIs through the surrounding fluid for small n. For high area fraction n > 0.4 the power law exponent for the spatial decay of [Formula: see text] begins to decrease, which suggests the HIs are more contributed from the 2D particle monolayer self for large n.
State Key Laboratory of Surface Physics, Department of Physicse, Fudan University, Shanghai, China ; Department of Applied Physics, Northwestern Polytechnical University, Xi'an, China ; Department of Physics, Jinan University, Guangzhou, China.
Wei
W
Zhang
State Key Laboratory of Surface Physics, Department of Physicse, Fudan University, Shanghai, China.
Song
S
Chen
State Key Laboratory of Surface Physics, Department of Physicse, Fudan University, Shanghai, China.
Na
N
Li
State Key Laboratory of Surface Physics, Department of Physicse, Fudan University, Shanghai, China.
Jia Zheng
JZ
Zhang
State Key Laboratory of Surface Physics, Department of Physicse, Fudan University, Shanghai, China ; Kavli Institute for Theoretical Physics China, CAS, Beijing, China.
Wei
W
Chen
D003102:Colloids / Q000737:chemistry*; D004058:Diffusion; D057446:Hydrodynamics; D012984:Software
D003102:Colloids