Atmospheric Chemistry and Physics Observation of neutral sulfuric acid-amine containing clusters in laboratory and ambient measurements

Abstract. Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been sub-stantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammo-nia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a micro-scopic molecular scale (from molecular sizes up to 2 nm) have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfu-ric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to parti-cle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectromete