Many of the atmospheric aerosol particles that end up as cloud droplets originate from the condensation of individual gas molecules. Few gases are as efficient at nucleating particles as iodine, but many can grow existing particles to sizes where they become relevant. Iodine is unique in that it can also get chemically converted within aerosol particles and come back into the gas phase. By recycling like this many times, it may help to nucleate many new particles that keep growing from the condensation of other vapors. It is unknown by what mechanism iodine is chemically converted before being re-emitted. Knowledge about the mechanism, how quickly and where the recycling occurs, is needed to accurately include this catalytic role of iodine for atmospheric aerosol particle formation in climate models. This project will reduce the knowledge gap with a novel method that allows to measure the re-emission, laboratory and field measurements, and state-of-the-art theoretical methods.

2025

2029