Recent advances in our understanding of atmospheric chemistry have made clear the importance of reliable photochemical and kinetic information regarding critical processes involving ozone and its photodissociation products, O(1D2) and O2(X3E-g). This proposal addresses specific questions concerning the efficiency with which uvphotolysis of O3 leads to the production of these reactive species and their subsequent fate during collisions with ambient molecules including H2O, HCL, and O3, itself. Special emphasis is placed on the development of reliable spectroscopic tools for the ultratrace detection of the energetic products of reaction and photodissociation; the information obtained from the proposed studies will provide entirely novel information concerning the OH(A - X) and O2(B - X) transitions. Together these experiments will yield new information concerning the chemical mechanisms of ozone production and depletion, and extend our ability to detect chemically labile species in the atmosphere.//