Rate constants for the quenching of metastable O 2 ( 1 Σ) molecules

Singlet molecular oxygen, O 2 ( 1 Σ ), 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 1 Σ ), the quenching rates for several important molecules have been obtained at room temperature. The following table summarizes measurements. Quencher Rate Constants (cm 3 /s) CH 2 (4.6 ± 0.5) × 10 −13 H 2 (7.0 ± 0.3) × 10 −13 N 2 (1.7 ± 0.1) × 10 −15 Cl 2 (4.5 ± 0.8) × 10 −16 CO (4.5 ± 0.5) × 10 −15 O 3 (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 CO 2 and O 3 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.