Abstract The electro-gravitational aerosol balance (EAB) is a method of measuring the mass of nearly monodisperse aerosol particles using a Millikan-type cell. We propose in the present study a procedure for evaluating and correcting for the work function imbalance between the opposing electrode surfaces of the EAB cell, which might produce a bias in the mass measurement. In this procedure, EAB measurement is conducted for the same particles in multiple configurations in which the EAB cell is inverted and/or the electrical polarity of the particles is reversed. The differences between the apparent masses obtained in the multiple configurations are used to evaluate the work function imbalance. This procedure was applied to 100 nm and 300 nm polystyrene latex particles. The work function imbalance was found to be 34.5 meV ± 3.8 meV (the number following the symbol ± indicates the expanded uncertainty with a coverage factor of 2), which, if not corrected for, would lead to a measurement bias of approximately 9.6% in terms of mass, or 3.2% in terms of diameter, of the 100 nm particles, an effect that cannot be left uncorrected for. The number average mass and diameter of the 100 nm particles after correction for the work function imbalance were 585.7 ag ± 6.3 ag and 101.71 nm ± 0.39 nm, respectively. The small uncertainties show that the EAB method with the procedure of correcting for the work function imbalance is suited to developing particle mass and size standards. It was also confirmed that the difference in mass between positively charged particles and negatively charged particles was negligibly small. The effect of the work function imbalance on measurement of the 300 nm particles was not significant. Copyright © 2020 American Association for Aerosol Research

中文翻译：

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通过电重力气溶胶平衡准确测定单分散粒子的质量和直径：电极表面之间的功函数不平衡的校正

摘要 电引力气溶胶天平 (EAB) 是一种使用密立根型池测量几乎单分散的气溶胶粒子质量的方法。我们在本研究中提出了一种评估和校正 EAB 电池相对电极表面之间功函数不平衡的程序，这可能会在质量测量中产生偏差。在此过程中，EAB 测量是针对多个配置中的相同粒子进行的，其中 EAB 单元被反转和/或粒子的电极性被反转。在多种配置中获得的表观质量之间的差异用于评估功函数不平衡。该程序适用于 100 nm 和 300 nm 聚苯乙烯胶乳颗粒。发现功函数不平衡为 34.5 meV ± 3。8 meV（符号后面的数字 ± 表示覆盖系数为 2 的扩展不确定度），如果不进行校正，将导致大约 9.6% 的质量测量偏差，或 3.2% 的直径测量偏差, 在 100 nm 粒子中，这种效果不容忽视。校正功函数不平衡后的 100 nm 颗粒的数均质量和直径分别为 585.7 ag ± 6.3 ag 和 101.71 nm ± 0.39 nm。小的不确定性表明带有校正功函数不平衡程序的 EAB 方法适用于制定粒子质量和尺寸标准。还证实带正电粒子和带负电粒子之间的质量差异小到可以忽略不计。功函数不平衡对 300 nm 粒子测量的影响不显着。版权所有 © 2020 美国气溶胶研究协会