COUPLED CHANNEL TREATMENT OF TRANSITIONS BETWEEN NA(2P1/2,MJ) AND NA(2P3/2,MJ') IN COLLISION WITH NA(2S1/2,MJ'')

Transitions between the Zeeman substates of Na(3p 2P1/2) and Na(3p 2P3/2) in collision with Na(3s 2S1/2) in thermal energy region are investigated by the close-coupling method. Rotational and spin-orbit couplings are taken into consideration, and potential energy functions generated by a quantum chemical calculation are employed. The cross sections strongly depend on the magnetic quantum numbers of the initial and final states. This dependence qualitatively coincides with an experimental observation in the presence of a weak magnetic field, although the magnetic field is not considered in the present calculation. Total cross section of the transition Na(2p3/2) --> Na(2p1/2) is calculated to be 2.7 X 10(2) angstrom2 in good agreement with experiment. The following two mechanisms are found to dominantly contribute to the total cross section: (1) Transitions among the molecular states of Na2, 3-PI-2u <-- --> 3-PI-1u and 3-PI-1u <-- --> 3-PI-0u, induced by the spin-rotation coupling, and (2) the transition, 1-SIGMA-0g+ <-- --> 1-PI-1g induced by the Coriolis coupling.