Key Laboratory of Cluster Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Phys Chem Chem Phys. 2023 Jun 28;25(25):16745-16752. doi: 10.1039/d3cp01198d.
By seeding clouds, new particle formation (NPF) has a substantial impact on radiation balance, bio-geochemical cycles and global climate. Over oceans, both methanesulfonic acid (CHS(O)OH, MSA) and iodous acid (HIO) have been reported to be closely associated with NPF events; however, much less is known about whether they can jointly nucleate to form nanoclusters. Hence, quantum chemical calculations and Atmospheric Cluster Dynamics Code (ACDC) simulations were performed to investigate the novel mechanism of MSA-HIO binary nucleation. The results indicate that MSA and HIO can form stable clusters multiple interactions including hydrogen bonds, halogen bonds, and electrostatic forces between ion pairs after proton transfer, which are more diverse than those in MSA-iodic acid (HIO) and MSA-dimethylamine (DMA) clusters. Interestingly, HIO can be protonated by MSA exhibiting base-like behavior, but it differs from base nucleation precursors by self-nucleation rather than solely binding to MSA. Due to the greater stability of MSA-HIO clusters, the formation rate of MSA-HIO clusters can be even higher than that of MSA-DMA clusters, suggesting that MSA-HIO nucleation is a non-negligible source of marine NPF. This work proposes a novel mechanism of MSA-HIO binary nucleation for marine aerosols and provides deeper insights into the distinctive nucleation characteristics of HIO, which can help in constructing a more comprehensive sulfur- and iodine-bearing nucleation model for marine NPF.
通过播云，新粒子形成（NPF）对辐射平衡、生物地球化学循环和全球气候有重大影响。在海洋上，甲烷磺酸（CHS（O）OH，MSA）和碘酸（HIO）都被报道与 NPF 事件密切相关；然而，关于它们是否可以共同成核形成纳米团簇，人们知之甚少。因此，进行了量子化学计算和大气团簇动力学代码（ACDC）模拟，以研究 MSA-HIO 二元成核的新机制。结果表明，MSA 和 HIO 可以形成稳定的团簇，通过多种相互作用，包括氢键、卤键和离子对之间的静电力，质子转移后，这些相互作用比 MSA-碘酸（HIO）和 MSA-二甲胺（DMA）团簇中的相互作用更加多样化。有趣的是，MSA 可以质子化 HIO，表现出碱的行为，但与碱成核前体不同，它不是通过自身成核，而是通过与 MSA 结合来成核。由于 MSA-HIO 团簇的稳定性更高，MSA-HIO 团簇的形成速率甚至可能高于 MSA-DMA 团簇，这表明 MSA-HIO 成核是海洋 NPF 的一个不可忽视的来源。这项工作提出了海洋气溶胶中 MSA-HIO 二元成核的新机制，并深入了解了 HIO 的独特成核特性，这有助于构建更全面的海洋 NPF 含硫和含碘成核模型。
