Formation and growth of particles in air: New insights from laboratory studies

Airborne particles are well known to negatively impact health and visibility, and to impact climate. Despite decades of elegant experimental, field and theoretical studies, much remains unknown about the fundamental mechanisms of the formation of new particles and how they grow in air. Interface chemistry is particularly important in the earliest stages of new particle formation since essentially all molecules are at the surface. While sulfuric acid, water and ammonia clearly play a role, less is known about other potential sources. Methanesulfonic acid, formed in the atmospheric oxidation of many organosulfur compounds, is one possible precursor. The results of studies of laboratory and theoretical studies of particle formation and growth from the reactions of methanesulfonic acid with amines and the impact of water on this process will be presented and the atmospheric implications discussed.