Photochemical transformations in ice: Implications for the fate of chemical species

A quantum yield of ϕ ice = 2.3 × 10 −4 (±4 × 10 −5 ) was determined for the photochemical degradation of 4‐nitrophenol over the wavelength range of 300 to 370 nm in ice pellets (pH 5.6). Five reaction products were identified: hydroquinone, benzoquinone, 4‐nitrosophenol, nitrate, nitrite, and the likely formation of organic polymers. The similarities of these results to the observations from 4‐nitrophenol photolysis in aqueous solutions indicate that similar mechanisms are operative in both phases. The photochemical decomposition of 4‐nitrophenol under conditions similar to those in polar snow and ice suggests that other direct and indirect photochemical process can occur in the polar ice/snow during spring and summer.