On the adsorption of NO and NO2 on cold H2O/H2SO4 surfaces

A static reaction chamber attached to a mass spectrometer was employed to study the adsorption of NO and NO2 onto cold surfaces of pure ice and liquid/solid 70 wt % H2SO4. No significant adsorption could be observed for surface temperatures in the range 193–243 K and NO/NO2 partial pressures of 10−2–10−5 mbar. This sets an upper limit on the uptake coefficients for both NO and NO2 of 5 · 10−5. The possible formation of nitrosyl sulphuric acid by adsorption of NO and NO2 on cold sulphuric acid particles is therefore unlikely to be of importance in the stratosphere.