Ab initio quantum mechanical study of the O(¹D) formation in the photolysis of ozone between 300 and 330 nm

Spin-allowed production of O(¹D) in the near-UV photolysis of ozone is studied using ab initio potential energy surfaces and quantum mechanics. The O(¹D) quantum yield, reconstructed from the absolute cross sections for eight initial vibrational states in the ground electronic state, is shown to agree with the measurements in a broad range of photolysis wavelengths and temperatures. Relative contributions of one- and two-quantum stretching and bending initial excitations are quantified, with the contribution of the antisymmetric stretch being dominant for λ < 330 nm. Large scale structures in the low-resolution quantum yield are shown to reflect excitations in the high-frequency short bond stretch in the upper electronic state. Spin-forbidden contribution to the O(¹D) quantum yield at wavelengths λ > 320 nm is estimated using ab initio energies of the triplet states and their spin-orbit couplings.