TY - JOUR
T1 - Translation-rotation decoupling of colloidal clusters of various symmetries
AU - Anthony, Stephen M.
AU - Kim, Minsu
AU - Granick, Steve
N1 - Funding Information:
S.A. acknowledges the NSF for financial support in the form of a Graduate Research Fellowship. This work was supported by the National Science Foundation Grant No. NSF-DMR-06-05947.
PY - 2008
Y1 - 2008
N2 - Single-particle tracking was used to measure the diffusion in aqueous suspension of dilute colloidal clusters, 2-9 μm in size, fabricated by joining 1.57 μm spheres into planar arrangements of various particle numbers and symmetries (doublet, trimer, square, pentamer, hexamer, and so forth). They were allowed to sediment close to a glass surface and their Brownian motion parallel to the surface, effectively in a two dimensional (2D) geometry, was imaged in a microscope in the presence of 3 mM monovalent salt to essentially screen electrostatic interactions. Geometric asymmetry produced systematically increasing discrepancy between the equivalent hydrodynamic radius of translation and rotation-tabulated in this paper. Our observations include cases where the effective hydrodynamic radius changes more rapidly for translation than rotation, the converse, and also cases where the effective hydrodynamic radius for translation changes significantly, while that of rotation is effectively constant. The significance is to document the connection between translational and rotational 2D mobilities for geometrical shapes not described by the Stokes-Einstein-Debye equations for spherical particles.
AB - Single-particle tracking was used to measure the diffusion in aqueous suspension of dilute colloidal clusters, 2-9 μm in size, fabricated by joining 1.57 μm spheres into planar arrangements of various particle numbers and symmetries (doublet, trimer, square, pentamer, hexamer, and so forth). They were allowed to sediment close to a glass surface and their Brownian motion parallel to the surface, effectively in a two dimensional (2D) geometry, was imaged in a microscope in the presence of 3 mM monovalent salt to essentially screen electrostatic interactions. Geometric asymmetry produced systematically increasing discrepancy between the equivalent hydrodynamic radius of translation and rotation-tabulated in this paper. Our observations include cases where the effective hydrodynamic radius changes more rapidly for translation than rotation, the converse, and also cases where the effective hydrodynamic radius for translation changes significantly, while that of rotation is effectively constant. The significance is to document the connection between translational and rotational 2D mobilities for geometrical shapes not described by the Stokes-Einstein-Debye equations for spherical particles.
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U2 - 10.1063/1.3043443
DO - 10.1063/1.3043443
M3 - Article
C2 - 19123520
AN - SCOPUS:58149234023
SN - 0021-9606
VL - 129
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 24
M1 - 244701
ER -