Reactions of excited species in the photolysis of ozone

Abstract

The primary step in the u.-v. photolysis of ozone may produce excited atomic and molecular fragments. It has been shown that, at λ= 254 nm, both O(¹D) and O₂(¹Δ_g) are formed with unit efficiency. O(¹D) may react with O₃ to yield either 2O(³P)+ O₂ or O^†₂+ O₂, where O^†₂ is vibrationally or electronically excited. O₂(¹Δ_g) reacts with ozone to yield O(³P)+ 2O₂. These secondary reactions are discussed with reference to partial and total quantum yields for the removal of O₃ and for the production of O(³P). Molecular oxygen quenches O(¹D) to yield some O₂(¹∑_g⁺) which can react with O₃. Quantum yields measured in the presence and absence of O₂ may be used to estimate the efficiency of the energy transfer from O(¹D) to O₂.