Fig. 4.

Insights into iodine-organic multiphase reactions fast-tracking marine new particle formation. Iodine released from the ocean surface is photolyzed and oxidized to form iodine oxides or iodine oxoacids (HIO₃ and HIO₂), which can nucleate to form IOPs or contribute to the early cluster growth by chemical activation of the prenucleation cluster. Within the recently formed ultrafine particles heterogeneous reactions between the higher iodine oxides and condensing alcohols or carbonyls from oxidation of marine VOCs lead to the formation of low volatility oxidized organics where the produced organic acids can further react with basic molecules (e.g., amines) to form highly hygroscopic salts, accelerating the early particle growth into Aitken mode and ultimately CCN. During this process, the higher iodine oxides are recycled, restarting the reaction sequence.