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Use of Electrostatic Classification Method to Size 0.1 mum SRM Particles. A Feasibility Study.

pdf icon Use of Electrostatic Classification Method to Size 0.1 mum SRM Particles. A Feasibility Study. (2876 K)
Kinney, P. D.; Pui, D. Y. H.; Mulholland, G. W.; Bryner, N. P.

Journal of Research of the National Institute of Standards and Technology, Vol. 96, No. 2, 147-176, March/April 1991.


aerosol generators; atomizers; particle size


The use of the electrostatic classification method for sizing monodisperse 0.1 mum polystyrene latex (PSL) spheres has been investigated experimentally. The objective was to determine the feasibility of using electrostatic classification as a standard method of particle sizing in the development of a 0.1 mum particle diameter Standard Reference Material (SRM). The mean particle diameter was calculated from a measurement of the mean electrical mobility of the PSL spheres as an aerosol using an electrostatic classifier. The performance of the classifier was investigated by measuring its transfer funciton, conducting a sensitivity analysis to verify the governing theoretical relationships, measuring the repeatability of particle sizing, and sizing NIST SRM 1691, 0.269 mum and NIST SRM 1690, 0.895 mum particles. Investigations of the aerosol generator's performance focused on the effect of impurities in the particle-suspending liquid on the resulting particle diameter. The uncertainty in particle diameter determined by electrical mobility measurements is found to be -3.3% to +3.0%. The major sources of uncertainty include the flow measurement, the slip correction, and a dependence of particle size on the aersol flow rate. It was found that the classifier could be calibrated to indicate the correct size to within 0.1% for both SRM particle sizes if the defined classification length is decreased by 1.9%.