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Size and Density Measurement of Core-Shell Si Nanoparticles by Analytical Ultracentrifugation



Kanokwan (. Nontapot, Vinayak Rastogi, Jeffrey A. Fagan, Vytautas Reipa


Si nanocrystals, terminated with cyclohexane and allylamine, were analyzed using analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and transmission electron microscopy (TEM). We found that AUC yielded equivalent particle size distribution data to other NP characterization techniques, while also providing important information not probed by techniques such as DLS regarding the relative size of the particle core and shell components, and the overall effective particle density. Estimates of particle core and shell dimensions are consistent with particle optical properties within the quantum confinement representation and available theoretical Si nanocrystal models. Measurement of sedimentation velocity in several solvents with the unlike densities presents a way to circumvent the ambiguity of simultaneous fitting of particle density and sedimentation coefficient and allows to significantly reduce the uncertainty in the particle hydrodynamic diameter estimates by finding the effective particle density value.


Silicon nanocrystal, core-shell nanoparticles, size measurement, analytical ultracentrifugation, dynamic light scattering
Created March 22, 2013, Updated November 10, 2018