Simplified mechanism for new particle formation from methanesulfonic acid, amines, and water via experiments and ab initio calculations
Simplified mechanism for new particle formation from methanesulfonic acid, amines, and water via experiments and ab initio calculations
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DOI：
10.1073/pnas.1211878109
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发表时间：
2012-11-13
影响因子：
11.1
通讯作者：
Finlayson-Pitts, Barbara J.
中科院分区：
文献类型：
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作者：
Dawson, Matthew L.;Varner, Mychel E.;Finlayson-Pitts, Barbara J.
空气中的颗粒物影响人类健康，并对能见度和气候产生重大影响。这些颗粒的主要部分来自气态前体的反应，以产生低挥发性产物，如硫酸和高分子量有机物，其成核形成新的颗粒。氨和最近的胺都在环境中普遍存在，也被认为是重要的贡献者。然而，准确预测实验室系统和空气中新颗粒的形成一直是个问题。在有机硫化合物的氧化过程中，气相甲磺酸与硫酸同时形成，两者都存在于沿海地区和内陆的颗粒中。我们在这里显示：（i）胺形成颗粒与甲磺酸反应，（ii）水蒸气是必需的，和（iii）颗粒的形成可以定量再现的半经验动力学模型支持的见解从量子化学计算可能的中间集群。这种方法可能更广泛地适用于室外，室内和工业环境中的颗粒形成的模型，并且准确的建模对于预测其对健康，能见度和气候的影响至关重要。
Airborne particles affect human health and significantly influence visibility and climate. A major fraction of these particles result from the reactions of gaseous precursors to generate low-volatility products such as sulfuric acid and high-molecular weight organics that nucleate to form new particles. Ammonia and, more recently, amines, both of which are ubiquitous in the environment, have also been recognized as important contributors. However, accurately predicting new particle formation in both laboratory systems and in air has been problematic. During the oxidation of organosulfur compounds, gas-phase methanesulfonic acid is formed simultaneously with sulfuric acid, and both are found in particles in coastal regions as well as inland. We show here that: (i) Amines form particles on reaction with methanesulfonic acid, (ii) water vapor is required, and (iii) particle formation can be quantitatively reproduced by a semiempirical kinetics model supported by insights from quantum chemical calculations of likely intermediate clusters. Such an approach may be more broadly applicable in models of outdoor, indoor, and industrial settings where particles are formed, and where accurate modeling is essential for predicting their impact on health, visibility, and climate.