A tutorial guide on new particle formation experiments using a laminar flow reactor
A tutorial guide on new particle formation experiments using a laminar flow reactor
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DOI：
10.1016/j.jaerosci.2021.105808
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发表时间：
2021-05-15
影响因子：
4.5
通讯作者：
Jen, Coty N.
中科院分区：
文献类型：
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作者：
Fomete, Sandra K. W.;Johnson, Jack S.;Jen, Coty N.
新粒子形成(NPF)产生了对流层中约50%的全球云凝结核。因此，NPF在气候中起着至关重要的作用。尽管在能够测量新形成的直径接近1纳米的气溶胶颗粒的仪器方面取得了进展，但由于大气的复杂成分和化学成分，NPF背后的机制仍然研究不足。成核是NPF的第一步，涉及到气体前体反应形成稳定的团簇；因此，了解成核反应背后的反应动力学是至关重要的。以前曾使用受控实验室实验来检查这些反应，这些反应可能在极低的反应物浓度(即百万分之一级，10(5)厘米(-3))或更低的情况下发生。成核实验需要原始的条件才能使反应在不受不可预测污染物干扰的情况下进行。这里，提出了一种低成本的流动反应器，它最大限度地减少了污染，并允许观察成核动力学。介绍了一个实例反应器的布置和设置，并对如何操作该反应器以保证清洁度和重复性进行了简要的讨论。此外，还描述了定量成核反应物的方法以及在该流动反应器系统中充分测量成核动力学的分析测量技术。这一实验方案可以用来表征成核反应，最终可以用来开发成核模型，这些模型对于预测气溶胶粒子如何影响气候至关重要。
New particle formation (NPF) produces about 50% of the global cloud condensation nuclei in the troposphere. As such, NPF plays a crucial role in climate. Despite advancements in instrumentation capable of measuring freshly formed aerosol particles down to similar to 1 nm in diameter, the mechanisms behind NPF remain understudied due to the complex composition and chemistry of the atmosphere. Nucleation is the first step of NPF and involves gaseous precursors reacting to form stable clusters; consequently, it is essential to understand the reaction kinetics behind nucleation reactions. Controlled laboratory experiments have previously been used to examine these reactions, which can occur at extremely low reactant concentrations (i.e., parts per quadrillion level, 10(5) cm(-3)) or lower. Nucleation experiments require pristine conditions for the reactions to proceed without interference from unpredictable contaminants. Here, a low-cost flow reactor is presented that minimizes contamination and allows for nucleation kinetics to be observed. The layout and setup of an example reactor are presented with a brief discussion on how to operate the reactor to ensure cleanliness and repeatability. In addition, methods for quantifying nucleation reactants as well as analytical measurement techniques to adequately measure nucleation kinetics in this flow reactor system are described. This experimental protocol can be employed to characterize nucleation reactions that can ultimately be used to develop nucleation models important for predicting how aerosol particles influence climate.