Microscopic Mechanisms of NO Hydrolysis on the Surface of Water Droplets.

Reactions of NO, in particular heterogeneous hydrolysis, play a vital role in determining the chemistry of the atmosphere. The NO heterogeneous hydrolysis reaction has been the subject of extensive research for decades, yet the physicochemical details of the mechanism have not been established. In this study, we show that this reaction can occur on the surface of a pure water droplet. We compute a relevant transition state for a nano-size model system and follow its evolution in time by means of ab initio molecular dynamics. This transition state, where NO has a strong ion-pair character, leads directly to HNO. Both electrophilic and nucleophilic mechanisms take place. It is suggested that corresponding simulations for hydrolysis in the bulk are desirable.