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Measurement of 100 nm Monodisperse Particles by Four Accurate Methods: Uncertainty and Traceability



George Mulholland, Kaleb Duelge, Vincent A. Hackley, Natalia Farkas, John A. Kramar, Keiji Takahata, Michael Zachariah, Hiromu Sakurai, Kensei Ehara


Accurate measurements of particle diameter are necessary for quantitative characterization of key aerosol properties including the Cunningham slip correction, charging probability, the diffusion coefficient, the coagulation coefficient, and optical properties. In this study we compare the particle size of nominal 100 nm spheres with a coefficient of variation of less than 2 % measured by four techniques with three traceable back to the wavelength of light. The instruments used are the differential mobility analyzer, atomic force microscopy, scanning electron microscopy, and an electrical-gravitational aerosol balance (EAB). The microscopy methods are traceable to the wavelength of light through the NIST Calibrated Atomic Force Microscope. A major focus of this paper is the quantitative estimates of the measurement uncertainty for each technique. The study shows the average particle size is within 3 % for all the methods. Possible reasons for the differences are discussed. The uncertainty in the EAB measurement has been reduced by accounting for the effect of the work function potential on the voltage between the two electrodes. While the calibration of existing aerosol measurements to an accuracy of 3 % would significantly improve the current measurements of size distribution, a validated uncertainty of less than 1 % would provide an impetus for improving the accuracy of key aerosol properties. A reduced uncertainty would also be important in addressing the current differences between the 100 nm size obtained by two national laboratories.
Aerosol Science and Technology


nanoparticle, differential mobility, electron microscopy, aerosol, electrical-gravitational aerosol balance, reference material


Mulholland, G. , Duelge, K. , Hackley, V. , Farkas, N. , Kramar, J. , Takahata, K. , Zachariah, M. , Sakurai, H. and Ehara, K. (2024), Measurement of 100 nm Monodisperse Particles by Four Accurate Methods: Uncertainty and Traceability, Aerosol Science and Technology, [online],, (Accessed May 26, 2024)


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Created February 12, 2024, Updated April 3, 2024