Recombination of Oxygen Atoms at High Temperatures as Measured by Shock-Tube Densitometry

Abstract

The rate of recombination of oxygen atoms has been measured by shock-tube x-ray densitometry in the range 1500°—2800°K. Mixtures of ozone, oxygen, and argon or krypton were driven with helium in a shock tube and density records obtained for each experiment. Within 2 μsec after the arrival of the shock wave the ozone had decomposed leaving an excess of oxygen atoms. The oxygen-atom concentration is subsequently determined by the density of the gas, and the recombination rate is obtained from the gradual decrease in density. The reaction O+O+O2→ lim k42O2is the dominant reaction in this system, and its rate, defined by the equation d[O2]/dt=k4[O]2[O2] is found to be k4=(6.81±0.54)×108(2200/T)(1.22± 0.53) liter2/mole2·sec. This result is in close agreement with that found by Rink from dissociation experiments.