Heterogeneous Reactions of NO3 and N2O5 with a Range of Organic Substrates

Although NO3 and N2O5 are important nighttime species in the troposphere, reactions between these gas-phase species and organic particles remain unexplored with few exceptions. These heterogeneous reactions may be important for several reasons. For example, these reactions may be a loss pathway for condensed-phase organic compounds in the atmosphere, which has implications for source apportionment. We have investigated heterogeneous reactions between NO3 and N2O5 and several organic surfaces and films such as organic self-assembled monolayers (SAMs), solid polycyclic aromatic hydrocarbon films (PAHs), liquid organic films, frozen organic films, and soot. These substrates and films are used as proxies for organic particles in the atmosphere. Determinations of the reactive uptake coefficients for NO3 and N2O5 on these different substrates will be presented. Since the studied substrates and films are used as proxies for organic particles in the atmosphere, we demonstrate how the uptake data for these reactions may be significant under atmospheric conditions.