Comparison of the spin–orbit selectivity of reactions involving atoms in a 2P or 3P state and a linear molecule in a Π or Σ state at very low temperature

In this work, we treat the general case of an atom in a 2P or 3P electronic state reacting with a linear molecule in a 2Π, 2Σ or 3Σ electronic state. We demonstrate that the spin–orbit selectivity of the rate constant at low temperatures (T<10 K) is associated with the different contributions to the long-range intermolecular potential calculated in the spin–orbit basis set of the reactants. We give examples of applications to a few reactions of astrophysical interest.