Wave packet dynamics of the N(4S)+O2(X 3Σg-)→NO(X 2Π)+O(3P) reaction on the X 2A′ potential energy surface

We report three-dimensional quantum calculations of total angular momentum J=0 reaction probabilities, J-shifting cross sections, and rate constants of the title reaction. Employing the real wave packet approach, we propagate wave packets corresponding to several O-2(v,j) initial levels on the X (2)A(') potential surface of Sayos As collision energy increases, the average probabilities first increase monotonically and then become nearly constant, while the cross sections rise in the overall energy range. Numerous probability resonances point out the formation of NOO collision complexes and NO final states. Rotational excitation in O-2 decreases the collisional energy thresholds and enhances the state-resolved rate constants, mainly at low temperature. O-2 vibrational excitation inhibits the reactivity, although the energy thresholds are still reduced. With respect to previous quasiclassical and mixed quantum-classical studies, we obtain lower thresholds and cross sections but similar rate constants, which are however lower than experimental rates. By inspection of the average properties of the wave packets, we suggest a qualitative reaction mechanism, we propose a modified J-shifting approximation, and we find a possible explanation of the low quantum reactivity on the present potential. (C) 2001 American Institute of Physics.