Thermal scattering of atoms by homonuclear diatomic molecules

The formal theory of scattering by a rigid rotator is applied to the problem of the rotational excitation and elastic scattering of homonuclear diatomic molecules by atoms. A statistical theory is employed to analyze the effects of the strong coupling which occurs between the different scattering channels. According to this theory the Massey-Mohr formula provides a good approximation to the total scattering cross-section, an upper limit of $\frac{1}{2}$ holds for the ratio of inelastic to total cross-sections and the probability of a rotational transition does not depend very sensitively on the corresponding change in the rotational quantum number. Numerical results are presented for the collision of argon and nitrogen at room temperature.