Measuring ultrafine aerosols by direct photoionization and charge capture in continuous flow
Measuring ultrafine aerosols by direct photoionization and charge capture in continuous flow
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通过连续流中的直接光电离和电荷捕获测量超细气溶胶
DOI：
10.1080/02786826.2018.1430350
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发表时间：
2018
影响因子：
5.2
通讯作者：
S. Hochgreb
中科院分区：
文献类型：
--
作者：
R. Nishida;A. Boies;S. Hochgreb
摘要直接紫外光电离使气溶胶纳米粒子不依赖于粒子和离子的碰撞而带电。在这项工作中，在粒子光电离过程中，施加一个低强度的电场来捕获电荷，因为它是从粒子在连续流动中光电发射的，从而产生了一种新的电流测量方法。与传统的基于光充电的测量设备一样，来自剩余光伏颗粒的不同电流也被测量到下游。这两个不同的测量电流与粒子的总光电活性面积成正比。通过将积分电流与实验光电离室中的带电烟尘粒子和离子的模拟结果进行比较，对粒子和离子(DIS)充电和输运的三维数值模型进行了评估。模型和实验表明，在一定的颗粒大小和浓度范围内，单一的经验常数KCI具有很好的定量一致性，这为所用的理论方程和数值方法提供了信心。版权所有(C)2018美国气溶胶研究协会
ABSTRACT Direct ultraviolet (UV) photoionization enables electrical charging of aerosol nanoparticles without relying on the collision of particles and ions. In this work, a low-strength electric field is applied during particle photoionization to capture charge as it is photoemitted from the particles in continuous flow, yielding a novel electrical current measurement. As in conventional photocharging-based measurement devices, a distinct electrical current from the remaining photocharged particles is also measured downstream. The two distinct measured currents are proportional to the total photoelectrically active area of the particles. A three-dimensional numerical model for particle and ion (dis)charging and transport is evaluated by comparing simulations of integrated electric currents with those from charged soot particles and ions in an experimental photoionization chamber. The model and experiment show good quantitative agreement for a single empirical constant, KcI, over a range of particle sizes and concentrations providing confidence in the theoretical equations and numerical method used. Copyright © 2018 American Association for Aerosol Research