The HCl+ClONO2 reaction rate on various water ice surfaces

The reaction ClONO2+HCl → Cl2+HNO3 on ice surfaces was investigated using a fast flow reactor coupled to a chemical ionization mass spectrometer. Rough and relatively smooth ice surfaces and single-crystal ice particles were employed to investigate the effect of the different surface morphologies on the reaction mechanism. Large reaction probabilities (γ>0.1), independent of HCl partial pressure in the range from 2×10−7 to 8×10−6 Torr, were measured on these three ice surfaces. These results are consistent with an ionic reaction mechanism involving HCl solvation on a liquid-like surface layer.