Molecular-level nucleation mechanism of iodic acid and methanesulfonic acid

Abstract. Both iodic acid (HIO3, IA) and methanesulfonic (CH3S(O)2OH, MSA) have been identified by field studies as important precursors of new particle formation (NPF) in marine areas. However, the mechanism NPF which IA MSA are jointly involved is still unclear. Hence, we investigated IA-MSA nucleation system under different atmospheric conditions uncovered corresponding nucleating at molecular level for first time, using a quantum chemical approach Atmospheric Cluster Dynamics Code (ACDC). The findings show that pure-IA rate was much lower than results CLOUD (Cosmics Leaving Outdoor Droplets) experiments. can promote cluster through stabilizing via both hydrogen halogen bonds, especially with temperatures, sparse IA, rich MSA. observations, indicating effect additional needs to be considered (e.g., H2SO4, HIO2, NH3, amines). revealed this study may help gain insight into joint sulfur- iodine-containing components on NPF.