A laser flash photolysis study of nitrous acid in the aqueous phase

The OH quantum yield from the photolysis of nitrous acid in the aqueous phase by the 355 nm light was measured to be 0.25 ± 0.03. OH radical thus formed reacted readily with HNO2 to produce NO2, which sequentially reacted with HNO2 to form the HNO2–NO2 adduct. The NO2 + HNO2 reaction was reversible with a forward rate constant of 3.76 × 107 dm3 mol−1 s−1 and a backward rate constant of 1.06 × 105 s−1. Decay of the HNO2–NO2 adduct would most likely generate HNO3 and NO at a rate constant of 3.0 × 103 s−1.