Laboratory Determination of the Rate Coefficient for Three-Body Recombination of Oxygen Atoms in Nitrogen

Abstract

 A laser-based measurement of the rate coefficient for O-atom three-body recombination at room temperature is reported. The experiment employs the pulsed output of a fluorine laser at 157.6 nm to achieve high degrees of photodissociation of molecular oxygen. In a high-pressure (1 atm) background of N₂, the produced oxygen atoms recombine in a timescale of several milliseconds. The O-atom population is monitored by two-photon laser-induced fluorescence at 845 nm, using a second laser with output near 226 nm. The measured value of the rate coefficient is (2.7 ± 0.3) × 10⁻³³ cm⁶s⁻¹ (1σ uncertainty), a value a factor of 2 lower than that currently adopted by the atmospheric modeling community.