New Photodissociation Processes in Ozone and Their Implications for Stratospheric Chemistry

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9528086 Houston This project will contribute to the understanding of ozone photodissociation and formation processes in the upper atmosphere. Several new mechanisms for additional ozone production in this region have been suggested recently. One of them involves the production of vibrationally excited oxygen molecules from the photodissociation of ozone, which could react with ground state oxygen molecules to form ozone. The first step of this process, production of vibrationally excited oxygen, has been demonstrated by the PI in earlier work. The second step, ozone formation, has not been unambiguously identified, however, there is indirect evidence from recent work. In this project, the technique of product imaging will be used in concert with laser photodissociation. In the imaging technique, a "snap-shot" of the three-dimensional velocity distribution of a state-selected reaction product is produced. From this, the internal energy distribution of the molecular oxygen fragment can be deduced. The objectives of this project are: (1) determine the wavelength dependence of the production of triplet oxygen in the vibrational states above the energetic threshold (v=26) for ozone formation via reaction with another oxygen molecule, (2) investigate the product distributions in the singlet dissociation channel.