Flash photolysis of ozone in oxygen and oxygen + hydrogen mixtures. Kinetics of molecular oxygen(1.SIGMA.g+) + ozone and atomic oxygen(1D) + hydrogen reactions

The flash photolysis of small amounts of O/sub 3/ in O/sub 2/ or O/sub 2/ + H/sub 2/ systems produced O(/sup 1/D) atoms which react either with O/sub 2/ or with H/sub 2/. Reaction with O/sub 2/ deactivates O(/sup 1/D) to O(/sup 3/P), which eventually re-forms O/sub 3/. Reaction with H/sub 2/ produces H and OH and leads to a permanent O/sub 3/ loss. The reciprocal of the fraction of O/sub 3/ lost is nearly proportional to the ratio of rates k/sub 2/(O/sub 2/)/k/sub 3/(H/sub 2/) as predicted for this competition. However, a small dependence on O/sub 3/ concentration indicates that several minor reactions also contribute to loss of O/sub 3/. Computer modeling, which takes into account all of these reactions, gives the value k/sub 3/(H/sub 2/+O(/sup 1/D)) = (6.5 +- 0.5) x 10/sup 10/ M/sup -1/ s/sup -1/, assuming k/sub 2/(O/sub 2/+O(/sup 1/D)) = 2.2 x 10/sup 10/ M/sup -1/ s/sup -1/. O(/sup 1/D) reaction with ground-state O/sub 2/(/sup 3/..sigma../sub g//sup -/) leads to a substantial amount of O/sub 2/(/sup 1/..sigma../sub g//sup +/) which reacts rapidly with more O/sub 3/. Modeling of the additional O/sub 3/ removal immediately after the flash yields k(O/sub 2/(/sup 1/..sigma../sub g//sup +/)+O/sub 3/) =more » (1.1 +- 0.2) x 10/sup 10/ M/sup -1/ s/sup -1/, in good agreement with most previous results.« less