Five samples of colloidal dispersions of gold nanorods with various aspect ratio were studied using methods based on light scattering. Transmission electron microscopy was used as a reference method. The advantages and disadvantages of the dynamic light scattering and nanoparticle tracking analysis methods for determination of the geometric parameters of nanoparticles, their concentration, monodispersity, as well as for detection of large aggregates and quasispherical impurities were given. It was shown that the method of depolarized dynamic light scattering can be used for determination of the geometric parameters of liquid dispersions of colloidal gold nanorods. Moreover, it was found that the presence of large impurities or particle aggregates in the sample strongly affects the measurement results. The presence of large particles in the dispersion can be determined using dynamic light scattering or nanoparticle tracking analysis methods. The method of dynamic light scattering was also found to be more sensitive to the presence of even a small amount of large impurities or aggregates in the sample. The monodispersity of a liquid dispersion of nanorods can also be estimated by dynamic light scattering and nanoparticle tracking analysis methods, and, comparing to electron microscopy, the measurement results can be considered more statistically reliable due to the analysis of a larger number of particles. It was found that the increase of spherical particles concentration in the composite dispersion of nanospheres and nanorods leads to a decrease in the contribution of the rotational mode in the total scattering intensity. In addition, the concentration of quasispherical impurities in samples of liquid dispersions of colloidal gold nanorods was calculated based on measurements of the depolarization degree of scattered light.
Optical Asymmetry and Nonlinear Light Scattering from Colloidal Gold Nanorods
