The reaction of OH with NO2 and the deactivation of O(1D) by CO

NO₂ was photolyzed with 2288 Å radiation at 300° and 423°K in the presence of H₂O, CO, and in some cases excess He. The photolysis produces O(¹D) atoms which react with H₂O to give HO radicals or are deactivated by CO to O(³P) atoms The ratio k₅/k₃ is temperature dependent, being 0.33 at 300°K and 0.60 at 423°K. From these two points, the Arrhenius expression is estimated to be k₅/k₃ = 2.6 exp(?1200/RT) where R is in cal/mole – °K. The OH radical is either removed by NO₂ or reacts with CO The ratio k₂/k^α is 0.019 at 300°K and 0.027 at 423°K, and the ratio k₂/k⁰ is 1.65 × 10^?5M at 300°K and 2.84 × 10^?5M at 423°K, with H₂O as the chaperone gas, where k^α = k₁ in the high-pressure limit and k⁰[M] = k₁ in the low-pressure limit. When combined with the value of k₂ = 4.2 × 10⁸ exp(?1100/RT) M^?1sec^?1, k^α = 6.3 × 10⁹ exp (?340/RT)M^?1sec^?1 and k⁰ = 4.0 × 10¹²M^?2sec^?1, independent of temperature for H₂O as the chaperone gas. He is about 1/8 as efficient as H₂O.