Effects of Mixing State on Black Carbon Measurements by Laser-Induced Incandescence
Effects of Mixing State on Black Carbon Measurements by Laser-Induced Incandescence
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DOI：
10.1080/02786820701199728
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发表时间：
2007-03
影响因子：
5.2
通讯作者：
N. Moteki;Y. Kondo
中科院分区：
文献类型：
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作者：
N. Moteki;Y. Kondo
对液滴测量技术公司（DMT）生产的基于激光诱导白炽（LII）技术的单颗粒碳烟光度计（SP2）的性能进行了实验室实验和理论计算。SP2用于测量黑碳（BC）或元素碳（EC）颗粒的质量和混合状态。在本研究中，石墨被用作EC的替代物。将质量当量直径为110-200 nm的石墨颗粒与有机液体（甘油和油酸）分层以产生直径高达650-800 nm的涂覆石墨。这些由SP2采样以测量波形（即，时间发展）的LII和散射信号。石墨颗粒的峰值温度和峰值LII信号与涂层厚度或涂层材料无关，在实验误差范围内。这些结果表明，EC的质量可以通过使用峰值LII信号来测量，而不受涂覆条件的干扰。还示出了散射和LII峰的时间之间的差可以用作EC上具有大于约100-200 nm的厚度的涂层的指示。LII和散射波形计算使用一个新开发的理论模型，考虑到控制的温度和蒸发速率的涂覆的石墨颗粒在激光束中的物理过程。计算再现了LII和散射信号观测波形的一般特征，为SP2数据的解释提供了坚实的理论基础。
Laboratory experiments and theoretical calculations were made to characterize the performance of a Single Particle Soot Photometer (SP2) manufactured by Droplet Measurement Technologies (DMT), which was designed to measure the mass and the mixing state of individual black carbon (BC) or elemental carbon (EC) particles, based on the laser-induced incandescence (LII) technique. In this study, graphite was used as a surrogate of EC. Graphite particles with mass equivalent diameters of 110–200 nm were layered with organic liquids (glycerol and oleic acid) to produce coated graphite with diameters up to 650–800 nm. These were sampled by the SP2 to measure the waveforms (i.e., time development) of the LII and scattering signals. The peak temperature and the peak LII signal of graphite particles were independent of the coating thickness or the coating material to within experimental errors. These results indicate that the mass of EC can be measured by using peak LII signal without interference by the coating conditions. It was also shown that the difference between the times of the scattering and LII peaks can be used as an indicator of coating on EC with thicknesses larger than about 100–200 nm. LII and scattering waveforms were calculated using a newly developed theoretical model that takes into account the physical processes controlling the temperature and evaporation rate of the coated graphite particle in the laser beam. The calculations reproduced the general features of observed waveforms of LII and scattering signals, providing a firm theoretical basis for the interpretation of the SP2 data.