Authors: R. Trutna, M. Liu, D. Chamberlin, J. Hadley
Affilation: Agilent Technologies, United States
Pages: 834 - 837
Keywords: nanoparticle size, UV-Visible, light scattering, dispersions
We present a spectroscopic technique for measuring particle size. The technique utilizes a UV-Visible spectrophotometer to measure the attenuation spectrum of a particle dispersion due to scattering. Using the Mie scattering theory, we compute the particle size distribution and particle concentration that best matches the measured scattering spectrum. While the operating range is material dependent, we have found that the instrument can measure particles sizes from 10 nm to 15 microns. The technique involves minimal sample preparation and clean up, and is fast. A measurement time of less than 10 seconds allows measurement of samples where dispersion stability is an issue or when the particles are dense and the sedimentation rate make traditional measurement techniques challenging. Since the technique does not rely on observing the Brownian motion of particles, the samples may be stirred or flowed during the measurement via the use of a stir bar accessory or utilizing flow through cells. We report experimental results comparing particle size measurements via this technique to SEM image analysis demonstrating the accuracy of the measurement. We also present experimental results demonstrating the capability of this technique to accurately measure the concentrations of populations in difficult bi- or multi-modal particle size distributions.