Diabatic crossings, dissociation

The main result of these first detailed experimental studies of the AI mechanism is that, even at thermal velocity, the system R -H follows a potential curve F ( R) that diabatically crosses an infinite number of potential curves dissociating into R+H, H being hydrogen in a Rydberg state, and continues to be well defined in the ionization continuum. We might mention that results on AI are also interesting because AI is the reverse reaction to the important process of dissociative recombination of molecular ions. 

The situation is less clear for the reaction between methylene and silylene here, in fact, an inspection of Fig. 8 for large values of R shows an avoided crossing of the TT and SS diabatic curves, leading to a small barrier. However, because of the limitations of these computations, this finding has to be taken with caution. Actually, a recent calculation indicates that silaethylene also dissociates through a least-motion path into a triplet methylene and a triplet silylene. The comparison between these two types of result for the reaction between methylene and silylene shows that it can be misleading in some cases to draw conclusions based only on diabatic curves rather than on the more informative diabatic surfaces. ... 

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