Uptake of Chlorine Dioxide by Model PSCs under Stratospheric Conditions

The uptake of chlorine dioxide by ice at temperatures approaching those needed for PSC formation in the Antarctic stratosphere was studied. The two approaches used in this investigation involved modeling the surface coverage using kinetic parameters obtained in an ultrahigh-vacuum surface experiment and comparing these results to the uptake measured in a flow tube apparatus. For an OClO gas phase concentration of 5 × 10 10 molecules/cm 3, a surface coverage of ≈2 x 10 -4±1 monolayers of OClO was estimated on the ice at 189 K from both methods. For an average OClO concentration in the Antarctic stratosphere of 2 x 10 9 molecules/cm 3, a surface coverage of 7 × 10 -6±1 monolayers of OClO on PSCs is predicted.