Effects of initial rotational quantum state excitations and thermal rate coefficient at room temperature for the H(2S) + NH(X3Σ-) → N(4S) + H2(X1Σg+) reaction

A full quantum mechanical wave-packet method was used to study the effects of initial rotational quantum state excitations including nonzero total angular momenta for the H(S-2) + NH(X-3 Sigma(-)) -> N(S-4) + H-2(X-1 Sigma(+)(g)) reaction system. Initial-state-specific reaction probabilities, integral cross sections and rate constants (RCs) averaged over all k states considered for rotational quantum number j from 0 to 6 are given, where k is the projection of diatomic rotational angular momentum onto the body fixed z axis. In general, according to the RCs, the j = 1 state is the most reactive one and the reactivity decreases as the rotational quantum number increases. An explanation for theoretical results based on ground rotational state only fitting well with the experimental observation is also given. At room temperature, the thermal RC averaged over 7 rotational states is slightly larger than that of the experimental measurement. However, if more initial rotational states are taken into account, the agreement will be improved.