Breakdown of Born-Oppenheimer approximation

Bunker, P.R., Moss, R.E. Breakdown of Born-Oppenheimer approximation—effective vibration-rotation Hamiltonian for a diatomic molecule. Mol. Phys. 1977,33,417-24 ... 

In this thesis work. Dr. Ren also studied the non-adiabatic effect in the F -I- D2 reaction, where the F ( Pi/2) is expected to be non-reactive according to the Bom-Oppenheimer approximation. He measured accurately the population ratio of F( P3/2) and F ( Pi/2) in the beam using synchrotron radiation single photon autoionization, then determined the relative reactivity of F and F with D2. For the first time, he found that F ( Pi/2) is more reactive than F( P3/2) at low collision energy, providing a clear case of the breakdown of Born-Oppenheimer approximation. This is the first accurate experimental measurement of the non-adiabatic effects of this important system. 

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