Interaction between carbon or iron aerosol particles and ozone

Ozone destruction by submicron particles has been experimentally investigated by measuring the ozone volume mixing ratio as a function of the particle concentration and by measuring the particle size with monolayer resolution. NOx-free O3 production in an air-like gas mixture is achieved by means of excimer UV radiation. Submicron carbon or iron aerosol particles are found to destroy ozone efficiently. For fresh carbon particles suspended in argon, the sticking coefficient of 03 to the particles is of the order of 10−4. Ozonised carbon or iron aerosol particles grow about 0.3 nm in diameter, which is attributed to adsorption of atomic oxygen and/or ozone molecules to the surface. If the ozonised carbon particles are separated from the ozone-containing gas stream, they shrink in size by more than 0.1 nm, indicating that carbon surface! atoms are transformed into CO or CO2. The results suggest that particles present in the stratosphere may represent a significant sink for O3.