THE OZONE DEFICIT PROBLEM - O-2(X,V-GREATER-THAN-OR-EQUAL-TO-26)-3) FROM 226-NM OZONE PHOTODISSOCIATION(O(P)

Highly vibrationally excited O-2(X(3) Sigma(g)(-), v greater than or e qual to 26) has been observed from the photodissociation of ozone (O-3 ), and the quantum yield for this reaction has been determined for exc itation at 226 nanometers. This observation may help to address the '' ozone deficit'' problem, or why the previously predicted stratospheric O-3 concentration is less than that observed. Recent kinetic studies have suggested that O-2(X(3) Sigma(g)(-), v greater than or equal to 2 6) can react rapidly with O-2 to form O-3 + O and have led to speculat ion that, if produced in the photodissociation of O-3, this species mi ght be involved in resolving the discrepancy. The sequence O-3 + h nu --> O-2(X(3) Sigma(g)(-), v greater than or equal to 26) + O; O-2(X(3) Sigma(g)(-), v greater than or equal to 26) + O-2 --> O-3 + O (where h nu is a photon) would be an autocatalytic mechanism for production o f odd oxygen. A two-dimensional atmospheric model has been used to eva luate the importance of this new mechanism. The new mechanism can comp letely account for the tropical O-3 deficit at an altitude of 43 kilom eters, but it does not completely account for the deficit at higher al titudes. The mechanism also provides for isotopic fractionation and ma y contribute to an explanation for the anomalously high concentration of heavy O-3 in the stratosphere.