Miao Shou-Kui, Jiang Shuai, Peng Xiu-Qiu, Liu Yi-Rong, Feng Ya-Juan, Wang Yan-Bing, Zhao Feng, Huang Teng, Huang Wei
Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics & Fine Mechanics, Chinese Academy of Sciences Hefei Anhui 230031 China.
School of Information Science and Technology, University of Science and Technology of China Hefei Anhui 230026 China
RSC Adv. 2018 Jan 16;8(6):3250-3263. doi: 10.1039/c7ra12064h. eCollection 2018 Jan 12.
Methanesulfonate (MSA), found in substantial concentrations in the atmosphere, is expected to enhance aerosol nucleation and the growth of nanoparticles, but the details of methanesulfonate clusters are poorly understood. In this study, MSA was chosen along with ammonia (NH) or three common amines and water (HO) to discuss the roles of ternary homogeneous nucleation and ion-induced nucleation in aerosol formation. We studied the structural characteristics and thermodynamics of the clusters using density functional theory at the PW91PW91/6-311++G(3df,3pd) level. The analysis of noncovalent interactions predicts that the amines can form more stable clusters with MSA than NH, in agreement with the results from structures and thermodynamics; however, the enhancement in stability for amines is not large enough to overcome the difference in the concentrations of NH and amines under typical atmospheric conditions. In addition, the favorable free energies of formation for the (MSA)(NH/amines)(HO) ( = 0-3) clusters at 298.15 K show that MSA could contribute to the aerosol nucleation process with binding NH/amines and HO up to = 3. There are strong temperature and humidity dependences for the formation of complexes; higher humidity and temperature promote the formation of larger hydrates. Finally, for the (MSA)(NH/amines)(HO) clusters, the evaporation rates were determined to further investigate the atmospheric implications.
大气中存在高浓度的甲磺酸盐（MSA），预计其会促进气溶胶成核和纳米颗粒的生长，但甲磺酸盐团簇的具体细节仍知之甚少。在本研究中，选择甲磺酸盐（MSA）并结合氨（NH₃）或三种常见胺类以及水（H₂O），以探讨三元均相成核和离子诱导成核在气溶胶形成中的作用。我们使用密度泛函理论在PW91PW91/6-311++G(3df,3pd)水平上研究了团簇的结构特征和热力学性质。对非共价相互作用的分析预测，胺类与甲磺酸盐（MSA）形成的团簇比氨（NH₃）更稳定，这与结构和热力学结果一致；然而，在典型大气条件下，胺类稳定性的增强不足以克服氨（NH₃）和胺类浓度的差异。此外，(MSA)(NH₃/胺类)(H₂O)ₙ（n = 0 - 3）团簇在298.15 K时有利的生成自由能表明，甲磺酸盐（MSA）通过结合氨（NH₃）/胺类和水（H₂O）直至n = 3，可能有助于气溶胶成核过程。配合物的形成对温度和湿度有很强的依赖性；较高的湿度和温度促进形成更大的水合物。最后，对于(MSA)(NH₃/胺类)(H₂O)ₙ团簇，测定了蒸发速率以进一步研究其大气影响。
