Collisional quenching of O2(1Δg)

Abstract

Abstract The paper reports determinations of rate constants for the physical deactivation of O2(1Δg) by gases present in the atmosphere. A modified discharge-flow technique was employed, and relative concentrations of O2(1Δg) were measured by a photoionization method. The rate constants for the process O2(1 Δg) ) + M → O2 + M (1) were ≤1.1 x 10-19, ≤ 2.1 x 10-19, ~2.4 x 10-18, ~3.9 x 10-18, ~ 1.5 x 10-17 (cm3molecule-1 s-1) for M = N2, Ar, O2, CO2, H2O respectively. The rate constant for quenching by dry air was measured directly to be 4.3 ± 0.7 x 10-19 cm3 molecule-1 s-1; this value is consistent with the most recent estimate based on [O2(1Δg)] in the upper atmosphere (3.5 ±1.0 x 10-19 cm3 molecule-1 s-1; W. F. J. Evans, private communication). Wall deactivation efficiencies varied from 1.2 x 10-5 to 2.3 x 10-5.