Diatom complexes energy transfer collision

The PR model considers, as a zero approximation, a motion of a diatom perturbed by the interaction with an atom placed at a fixed distance R from the center of mass of a diatom. For a particular case of a planar collision, this motion corresponds either to vibration or to hindered rotation of the diatom. Adiabatically-perturbed rotational-vibrational states of a collision complex are coupled by the relative radial motion. This coupling induces transition between different adiabatic channel states the nature of these transitions is such that near-resonant channels are strongly favored [31-33]. The latter dynamical property allows one to regard the R-mode as a spectator mode and to consider the energy transfer as a pure VR event. 

---