Rate constants for the quenching of metastable O2(1Σ) molecules

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Abstract
Singlet molecular oxygen, O2(1Σ), is one of the important intermediate species in the atmospheres of Earth, Mars, and Venus. To elucidate the chemistry of this excited molecular oxygen, a series of kinetic measurements have been undertaken using the flow‐discharge/optical‐emission technique. By monitoring the characteristic emission (762 nm for 1Σ), the quenching rates for several important molecules have been obtained at room temperature. The following table summarizes measurements. Quencher Rate Constants (cm3/s) CH2 (4.6 ± 0.5) × 10−13 H2 (7.0 ± 0.3) × 10−13 N2 (1.7 ± 0.1) × 10−15 Cl2 (4.5 ± 0.8) × 10−16 CO (4.5 ± 0.5) × 10−15 O3 (2.2 ± 0.3) × 10−11 2,3 DBM‐2 (6.0 ± 0.1) × 10−13 The error limits represent one standard deviation. The systematic error is estimated to be about 15%. For CO2 and O3 molecules, the quenching rate constants were also measured in the temperature range of 245–362 K. In both reactions, negligible temperature dependences (with the activation energy less than 0.6 kcal/mole) were observed.