Kinetic Isolation of Reaction Intermediates on Ice Surfaces. Precursor States of SO₂ Hydrolysis

We studied the interaction of SO₂ with ice films at temperatures above 80 K, with emphasis on the examination of the precursor states of SO₂ hydrolysis, or SO₂ surface complexes. Cs⁺ reactive ion scattering (RIS) and low energy sputtering (LES) techniques were used to examine the surface reaction products, in conjunction with temperature-programmed desorption (TPD) to monitor the desorbing species. The study indicated that the reaction of SO₂ with the ice surface occurred through several distinct intermediate states, including a solvated SO₂ species, a DSO₂ species, and a strongly ionic molecular species, and these intermediates could be isolated on the ice surface due to kinetic trapping.