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Dynamic Light Scattering of Rigid Rods – A Universal Relationship on the Apparent Diffusion Coefficient as Revealed by Numerical Studies and Its Use for Rod Length Determination
Author(s) -
Liu Tao,
Xiao Zhiwei
Publication year - 2012
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201200154
Subject(s) - dynamic light scattering , diffusion , rod , coupling (piping) , rotational diffusion , scattering , light scattering , chemistry , coupling coefficient of resonators , physics , materials science , optics , crystallography , thermodynamics , quantum mechanics , medicine , alternative medicine , pathology , anisotropy , resonator , nanoparticle , metallurgy
Numerical simulations are performed to study the diffusion behaviors of rigid rods examined by dynamic light scattering (DLS). It was identified that the apparent diffusion coefficient, D p , determined by DLS obeys a universal relationship D p / D G = f( qL ) = 1.1804 + 0.1764 × tanh [11.799× tan −1 ( qL ) ‐17.169], where D G , L , and q are the mass‐of‐center diffusion coefficient, length of the rod, and scattering vector, respectively. This relationship delineates the DLS experiments into weak ( qL < 4.0), intermediate (4.0 < qL < 20.0), and strong translation–rotation coupling regime ( qL > 20.0). In weak (strong) coupling regime, D p is a measure of D G (D // ‐ longitudinal diffusion coefficient) of the rods. In addition, if DLS is performed in the intermediate coupling regime, the rod length can be determined by solving D p / D G = f( qL ).