Department of Chemistry, University of California, Berkeley, CA 94720

A new model for calculating the average energies in product rotational, vibrational, and translational degrees of freedom in photodissociation reactions involving substantial exit barriers is presented. The model is discussed as a logical extension of the impulsive model that includes statistical partitioning of energy in excess of the barrier. Calculations are performed using the new model on the photodissociation of acetone and acetic acid. The results are compared to experiments and to other models for unimolecular dissociation.