Enhancement of Atmospheric Nucleation Precursors on Iodic Acid-Induced Nucleation: Predictive Model and Mechanism
Fangfang Ma, Hong‐Bin Xie, Rongjie Zhang, Lihao Su, Qi Jiang, Weihao Tang, Jingwen Chen, Morten Engsvang, Jonas Elm, Xu‐Cheng He
Abstract
High Resolution Image Download MS PowerPoint Slide Iodic acid (IA) has recently been recognized as a key driver for new particle formation (NPF) in marine atmospheres. However, the knowledge of which atmospheric vapors can enhance IA-induced NPF remains limited. The unique halogen bond (XB)-forming capacity of IA makes it difficult to evaluate the enhancing potential (EP) of target compounds on IA-induced NPF based on widely studied sulfuric acid systems. Herein, we employed a three-step procedure to evaluate the EP of potential atmospheric nucleation precursors on IA-induced NPF. First, we evaluated the EP of 63 precursors by simulating the formation free energies (Δ G ) of the IA-containing dimer clusters. Among all dimer clusters, 44 contained XBs, demonstrating that XBs are frequently formed. Based on the calculated Δ G values, a quantitative structure–activity relationship model was developed for evaluating the EP of other precursors. Second, amines and O/S-atom-containing acids were found to have high EP, with diethylamine (DEA) yielding the highest potential to enhance IA-induced nucleation by combining both the calculated Δ G and atmospheric concentration of considered 63 precursors. Finally, by studying larger (IA) 1–3 (DEA) 1–3 clusters, we found that the IA-DEA system with merely 0.1 ppt (2.5×10 6 cm –3 ) DEA yields comparable nucleation rates to that of the IA–iodous acid system.