Uptake and collision dynamics of gas phase ozone at unsaturated organic interfaces

Abstract

The uptake of gas phase ozone and the collision rate between ozone and double bonds at three different unsaturated organic interfaces with vapor are studied using classical molecular dynamics computer simulations. The organic systems are a self-assembled monolayer of 1-octenethiolate molecules adsorbed on a gold surface, liquid 1-tetradecene, and a monolayer of 1-oleoyl-2-palmitoyl- sn-glycero-3-phosphocholine molecules adsorbed at the water liquid/vapor interface. The structural features of the neat organic systems are characterized and correlated with the dynamics in the presence of gas phase ozone molecules. The collision rate between ozone and a double bond is sensitive to several factors, including the extent of localization of the double bonds in the system and the distance that ozone diffuses into the organic phase. However, the average lifetime of a collision between ozone and a double bond is independent of the organic system. A comparison of the simulation results with experimental results from these systems shows good agreement. The results are discussed in the context of the oxidative processing of organic aerosols in the atmosphere.