Decomposition of Ozone by O(1D)

摘要

Photometric measurements of ozone decomposition following flash photolysis of O3mdash;inerthyphen;gas mixtures are interpreted in terms of the timehyphen;dependent quantum yield. Decomposition occurs in time segments which contribute increments to the quantum yield that depend on temperature, pressure, and sample composition. A major portion of the reactionOlpar;1Drpar;plus;O3rarr;2O2,thinsp;thinsp;kge;2.3times;109litersol;molemiddot;secis complete during the photolysis flash and has no temperature dependence in the range 205deg;mdash;298deg;K. Processes which further enhance the quantum yield are much slower and depend on temperature, inerthyphen;gas pressure, and composition in a way that has some correlation with the effectiveness of the gas in deactivating vibrationally excited O2dagger;. In N2a factor of 2 less O3is decomposed by the end of a flash than in He or Ar, indicating deactivation of the O(1D) by N2. The quantum yield is smaller in N2than in He or Ar but qualitatively similar in its pressure dependence. Some limitations in accounting for the results by an energy chain mechanism are discussed.