A Near‐Comprehensive Evaluation on the Enhancing Potential of Atmospheric Organic Acids for Sulfuric Acid‐Dimethylamine Nucleation

Abstract Sulfuric acid (SA)‐dimethylamine (DMA) nucleation has been identified as a dominant pathway for aerosol nucleation in polluted megacities. However, it remains uncertain whether this mechanism alone can fully account for the nucleation rates observed under ambient conditions. Organic acids (OAs) are known to enhance SA‐DMA nucleation, but the enhancing potential (EP) of many OAs is still unclear. Here, we developed a high‐throughput predictive model for the EP of OAs, using the formation free energies (Δ G ) values of trimers formed by OAs, SA, and DMA as a critical parameter for EP assessment. We predicted the concentrations of (OA) 1 (SA) 1 (DMA) 1 trimers under ambient conditions and identified 2‐methylglutaric acid (iC 6 ) as the OA with the highest EP for SA‐DMA nucleation among the 33 selected OAs. By exploring the detailed formation mechanism of larger iC 6 ‐SA‐DMA clusters, we found that iC 6 enhances the SA‐DMA nucleation mainly by forming (iC 6 ) 1 (SA) y (DMA) z ( y = 1–2, z = 1–3) clusters, clarifying the OA can participate in SA‐DMA nucleation as a component. The nucleation rates are enhanced up to 80‐fold compared to SA‐DMA nucleation at 278.15 K, presenting a significantly higher EP than previously studied OAs. The strong synergistic nucleation of OAs‐SA‐DMA might play an important role in aerosol formation.