Collisional quenching of O(1D) by O(3P)

Metastable O(1D) atoms may be quenched in collisions with ground state O(3P) atoms by transitions in the avoided crossing regions of the three lowest 3[Pi]g states of O2 of which the lowest separates to O(3P) + O(3P) and the two upper to O(3P) + O(1D). Quantal calculations of the adiabatic potential energy curves of the 3[Pi]g , states are carried out with particular attention to an avoided crossing region in the lowest two states around a nuclear separation of 3.2a0. Diabatic potential matrix elements are constructed from the adiabatic curves by imposing the requirement that they be smooth everywhere. A multistate diabatic formulation is used to describe the scattering and the cross-sections for the collision-induced quenching of O(1D) atoms are calculated.The rate coefficient for the quenching of O(1D) atoms by O(3P) atoms is obtained as a function of temperature. At 1000 K, the value is 1.0 x 10-11 cm3 s-1, accurate probably to a factor of two. The theoretical rate coefficient is consistent with the empirical value inferred from upper atmosphere data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28609/1/0000418.pd