Vibrational and translational energy effects in the abstraction and exchange reactions of NH+3 with D2

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Abstract
We present a study of the abstraction and exchange reactions of NH+3 with D2 yielding NH3D++D and NH2D++HD, respectively. The translational energy of these experiments was fixed at 0.50 eV, while the vibrational energy of the ammonia cations was selected at values between 3.3 and 4.9 eV by a charge exchange technique. The flux distributions for the two distinct reaction products were quite different, indicating different precursors to their formation. The abstraction reaction products were backward scattered in the center-of-mass reference frame, while sharp forward–backward scattering of the exchange products suggested the participation of a transient intermediate living a fraction of a rotational period. The angular distribution for exchange became more symmetric about 90° with decreasing reagent vibrational energy, further supporting the participation of an intermediate complex. The product kinetic energy distributions for both processes broadened with increasing vibrational energy. This observation is consistent with partitioning of the total available energy of the incoming reagents into exchange product degrees of freedom as one would expect for a transient complex. The participation of the vibrational energy in the abstraction process is consistent with vibration–translation energy transfer from the ν2 bending mode of NH+3 to relative translation of the products.