Highly vibrationally excited O₂(X³σ_g^–, v ≥ 26) has been observed from the photodissociation of ozone (O₃), and the quantum yield for this reaction has been determined for excitation at 226 nanometers. This observation may help to address the "ozone deficit" problem, or why the previously predicted stratospheric O₃ concentration is less than that observed. Recent kinetic studies have suggested that O₂(X³σ_g^–, v ≥ 26) can react rapidly with O₂ to form O₃ + O and have led to speculation that, if produced in the photodissociation of O₃, this species might be involved in resolving the discrepancy. The sequence O₃ + hν → O₂(X³σ_g^–, v ≥ 26) + O; O₂(X³σ_g^–, v ≥ 26) + O₂ → O₃ + O (where hν is a photon) would be an autocatalytic mechanism for production of odd oxygen. A two-dimensional atmospheric model has been used to evaluate the importance of this new mechanism. The new mechanism can completely account for the tropical O₃ deficit at an altitude of 43 kilometers, but it does not completely account for the deficit at higher altitudes. The mechanism also provides for isotopic fractionation and may contribute to an explanation for the anomalously high concentration of heavy O₃ in the stratosphere.