Non-adiabatic unimolecular dissociation of polyatomic molecules. II. The thermal dissociation of nitrous oxide

The theory presented in part I of this series is applied to the non-adiabatic spin-forbidden thermal dissociation N₂O(¹Σ⁺)→N₂(¹Σ⁺_g)+O(³P) as a test case. The molecular model is multidimensional and includes all vibrational modes of the molecule. Specifically considered is the fact that the initial singlet state of N₂O is linear and the final triplet state is bent. The best available data are used for describing the intersection of singlet and triplet potential energy surfaces. Calculated microcanonical rate constants are averaged over Boltzmann distribution of energies and compared with k_co, the high-pressure rate constant deduced from experiment. The agreement between theory and experiment is satisfactory. Analysis of the calculations shows that the driving force for the N₂O dissociation is the flow of energy into the bending vibrations. This is because the bendings have very different equilibrium angles in the initial and final states.