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Luan Nguyen ACF Abstract FY10

Energy distribution in the triplet channels of ozone photodissociation

Conference Name: 2009 Symposium on Chemical Physics

Photodissociation of ozone in the Hartley band (4 eV < hv 6 eV) yields roughly 90% of its products in the O( 1D) + O21a Δ) singlet channel, and most of the remainder in the O(1P ) + O2(X3Σ¯g ) triplet channel.  The triplet products are produced by a transition between the initially excited B diabatic state and the repulsive R state of ozone, and have a broad distribution of kinetic energies centered around 2 eV. The translational energy distribution as measured by Brouard and coworkers at 226 nm shows reproducible structure with three distinct maxima corresponding to O2(X3Σ¯g ) in vibrational levels near v = 7, 12, and 16; between these maxima the measured distributions fall by about 10%. The measured distributions at 248 nm are similar. The broad features of the distribution are reproduced by surface hopping calculations on new B and R potential surfaces, though the computed distribution is less structured. The maxima in the vibrational and translational energy distributions are clearly related to maxima in the distribution of the emerging O2 bond lengths at the time the B/R crossing is encountered. Explorations of the physical basis of the translational energy distribution will be presented.