Ozone Ultraviolet Photolysis. III. Disposition of Vibrational Energy

Absorption by the Schumann—Runge $B^3{\Sigma }_u^{-}{\mathrm{\leftarrow X}}^3{\Sigma }_g^{-}$ system of O₂ was measured in order to identify the products of the $\mathrm{O}{(}^1\mathrm{D)+}{\mathrm{O}}_3$ reaction. These products are found to be $${\mathrm{O}}_3+\mathrm{O}{(}^1\text{D)→ 2}\mathrm{O}{(}^3\mathrm{P)+}{\mathrm{O}}_2,$$ $${\mathrm{O}}_3+\mathrm{O}{(}^1\text{D)→2}{\mathrm{O}}_2^{†}$$ with $k_{2{\mathrm{a}}^{\prime }}{\text{≳10k}}_{2{\mathrm{a}}^{\mathrm{\prime \; \prime }}}$ . The ${\mathrm{O}}_2^{†}$ product is observed in states $v^{\mathrm{\prime \; \prime }}\text{≤ 30}$ and is apparently formed in all levels up to the dissociation limit. The formation and disappearance of vibrationally excited ${\mathrm{O}}_2^{†}$ are correlated with measurements of changes in ozone absorbance that are usually attributed to vibrational excitation. Under marginally isothermal and nonisothermal conditions ozone is excited to a nonequilibrium energy distribution, probably by vibration→vibration energy transfer from ${\mathrm{O}}_2^{†}$ . The rates of all processes having an activation energy are enhanced by this excitation.