The photolysis of ozone by ultraviolet radiation V. Photochemical formation of O2(1Δg)

The photolysis of ozone at λ = 254 nm has been studied in a tim e-resolved flow system using helium , argon and nitrogen as carrier gases. Radiation of the O2(1Δg -> 3Σg) system at λ = 1.27 μm was the only detectable optical emission from the photolysis products. Kinetic studies established directly that O2(1Δg) is a primary product of ozone photolysis at λ = 254 nm O3 + hv - > O2(1Δg) + O(1D). Absolute calibration of the radiation detector for [O2(1Δg)] and measurement of the extent of ozone photolysis provided a method for the evaluation of ϕ1 the quantum efficiency for O2(1Δg) formation in (1). ϕ1 was found to be essentially unity . Some possible implications of the results to the photolysis of ozone + oxygen mixtures are discussed. The measurement of ϕ1 permits calculations to be made of expected [O2(1Δg)]— altitude profiles in the atmosphere. The results of a rocket determination of the altitude profile are compared with a calculated profile.