Journal of Physical Chemistry, Vol.99, No.37, 13637-13646, 1995
Fully Quantum-State Resolved Study of NO2 Photodissociation - Correlated No((2)Pi(Omega),V=0,J,Lambda)+o(P-3(J)) Distributions
Relative O(P-3(j=2,1,0)) spin-orbit populations correlated with specific NO[(2) Pi(Omega=1/2,3/2); v = 0; J; Lambda = Pi(A’), Pi(A ")] product states were obtained following photolysis of NO2 at excess energies E(not subset of) = 390, 425, and 1054 cm(-1). These-fully quantum state-resolved measurements were carried out by recording spatial profiles of recoiling NO((2) Pi(Omega),J,Lambda) products using polarized radiation for photolysis and state-selective laser ionization detection. The relative O(P-3(j)) populations correlated with each NO((2) Pi(Omega),J,Lambda) state show marked fluctuations at each excess energy as a function of rotational state and h-doublet component. The relative populations also fluctuate as a function of excess energy. The O(P-3(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(P-3(1)):O(P-3(2)) population ratios correlated with the ground NO((2) Pi(1/2)) state are colder than the corresponding ratios correlated with the excited NO((2) Pi(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((2) Pi) + O(P-3) dissociation channel.
Keywords:LASER-INDUCED GRATINGS;EXPANSION-COOLED NO2;UNIMOLECULAR REACTION;TRANSITION-STATES;NITROGEN-DIOXIDE;PHOTOFRAGMENT SPECTROSCOPY;ANGULAR-DISTRIBUTIONS;FREE JETS;DISSOCIATION;DYNAMICS