Radiative association of C(3 P) and N(4 S) atoms: From semi-classical theory to coupled-states quantum dynamics

Abstract: In the present work formation of the CN radical through radiative association is simulated using both semi-classical and quantum mechanical theories. The rate coefficient for temperatures from 40 K to 1900 K has been computed using the Breit-Wigner theory to account for the resonances. Comparison with the results obtained by the semi-classical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. Furthermore, the role of the spin-orbit and rotational couplings is investigated. Comparison of the energy-dependent rate coefficients calculated with and without spin-orbit and rotational couplings shows that the couplings effect the low-energy part of the rate coefficient.