光散乱式パーティクルカウンタを用いたサブミクロン鉱物粒子の粒径分布測定における非球形性の影響

概要

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This paper addresses the issue of measuring the size distribution of nonspherical mineral dust particles by use of an optical particle counter (OPC) on the basis of comparison with transmission electron microscopic (TEM) analysis by a laboratory experiment and the theoretical computation of light scattering by nonspherical particles. The dust particles were monodispersed in the electrical mobility radius of 0.25 and 0.5 μm and their size distribution were measured with the OPC and TEM and compared. The volume equivalent mode radii obtained with the OPC was 0.06-0.09 μm larger than that obtained with the TEM. The size distribution width (standard deviation) obtained with the OPC was 5-13 % larger than that obtained with the TEM. Theoretical computation of the light scattering by triaxial spheroids showed the large variation in the light scattering intensity depending on the particle orientation, which can result in the large size distribution width obtained with the OPC. These results show that particle nonsphericity critically affects the measurement of dust by use of the OPC and care should be taken in utilizing the measured size distribution.
日本エアロゾル学会の論文
2008-12-20