Measurement of Particle Asymmetry Using Cross-Correlation Techniques
Most static scattering1 techniques measure orientation averaged scattering factors of particles in suspension. Information on particle shape is difficult to obtain from such results. Similarly, the technique of dynamic light scattering will conventionally measure an ‘equivalent sphere’ hydrodynamic radius of the particles in suspension although for highly asymmetric particles (ie long rods) an estimate of the rotational diffusion constant can be obtained from multiangle linewidth measurements2,3. For small particles with only slight asymmetry the change in dynamic scattering linewidth with angle becomes comparable with that seen due to sample polydispersity alone and information on rotational diffusion and shape cannot be obtained from the data.
KeywordsEquivalent Sphere Rotational Diffusion Prolate Ellipsoid Number Fluctuation Spherical Silica Colloid
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