Rapid iodine oxoacid nucleation enhanced by dimethylamine in broad marine regions

Zu, Haotian; Chu, Biwu; Lu, Yiqun; Liu, Ling; Zhang, Xiuhui

Recent experiments have revealed a vital nucleation process of iodic acid (HIOinline-formula3) and iodous acid (HIOinline-formula2) under marine boundary layer conditions. However, HIOinline-formula3–HIOinline-formula2 nucleation may not effectively drive the observed rapid new particle formation (NPF) in certain coastal regions influenced by urban air masses. Dimethylamine (DMA) is a promising basic precursor to enhance nucleation considering its strong ability to stabilize acidic clusters and the wide distribution in marine atmosphere, while its role in HIOinline-formula3–HIOinline-formula2 nucleation remains unrevealed. Hence, a method combining quantum chemical calculations and Atmospheric Cluster Dynamics Code (ACDC) simulations was utilized to study the HIOinline-formula3–HIOinline-formula2–DMA nucleation process. We found that DMA can preferentially accept the proton from HIOinline-formula3 as a basic precursor in the most stable configurations of HIOinline-formula3–HIOinline-formula2–DMA clusters. Kinetically, the participation of DMA in the cluster formation pathways of the iodine oxoacid system could be significant at the 10inline-formula−1 to 1 pptv level of [DMA]. Furthermore, DMA can enhance the cluster formation rates of the HIOinline-formula3–HIOinline-formula2 system in marine and polar regions near DMA sources more than 10inline-formula3-fold. Compared to the classical nucleation mechanism, the HIOinline-formula3–HIOinline-formula2–DMA mechanism exhibits strong nucleation ability, worthy of consideration as a promising mechanism in marine and polar regions rich in amine sources. The newly proposed HIOinline-formula3–HIOinline-formula2–DMA ternary mechanism might provide an explanation for some missing fluxes of atmospheric iodine particles.



Zu, Haotian / Chu, Biwu / Lu, Yiqun / et al: Rapid iodine oxoacid nucleation enhanced by dimethylamine in broad marine regions. 2024. Copernicus Publications.


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