Overall, the F¯NH3 cryo-SEVI spectrum comprises a very rich resonance structure spanning the exit channel, the transition state region, and states above the reactant asymptote. In contrast to other bimolecular transition states studied with this technique, the vibrational structure cannot be explained in terms of a high-frequency hydrogen atom motion and a much lower frequency stretching motion involving the heavier atoms. The complexity of the spectrum reflects the fact that F + NH3 is not a simple hydrogen transfer reaction because the geometry of the NH3 moiety evolves significantly en route to the HF + NH2 products. Hence, assignment of the vibrational structure is possible only by comparison with multidimensional quantum dynamics calculations.