Fully quantum-state resolved study of NO₂ photodissociation. Correlated NO(²Π_Ω, ν = 0 J,A) + O(³P_j) distributions

Relative O(³P_j = 2.1.0) spin-orbit populations correlated with specific NO[²Π_Ω = 1/2 , 3/2; ν = 0; f; Λ = Π(A′), Π(A″)] product states were obtained following photolysis of NO₂ at excess energies E^± = 390, 425, and 1054 cm^-1. These fully quantum state-resolved measurements were carried out by recording spatial profiles of recoiling NO(²Π_Ω, J, Λ) products using polarized radiation for photolysis and state-selective laser ionization detection. The relative O(³P_j) populations correlated with each NO(²Π_Ω, J, Λ) state show marked fluctuations at each excess energy as a function of rotational state and Λ-doublet component. The relative populations also fluctuate as a function of excess energy. The O(³P_j) spin-orbit population ratios, when averaged over all measurements, exhibit distributions that are colder than statistical, in agreement with previous results. In particular, we find that, on average, O(³P₁):O(³P₂) population ratios correlated with the ground NO(²Π _1/2 ) state are colder than the corresponding ratios correlated with the excited NO(²Π_3/2) spin-orbit state. These results are in agreement with the state-specific calculations of Katigiri and Kato [J. Chem. Phys. 1993, 99, 8805] and are discussed in terms of long-range nonadiabatic transitions among electronic states correlating asymptotically with different spin-orbit states of the ground NO(²Π) + O(³P) dissociation channel.