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This article presents detailed internal and kinetic energy dependent cross sections and reaction rates for the hydrogen atom transfer processes N+2(X 2Σ+g, v+=0–4, J+=2)+H2→N2H++H, which were obtained under single-collision conditions in a guided-ion beam/scattering gas experiment. Preparation of ions in specific states relied on single-color excitation within a resonantly enhanced (2+1) multiphoton ionization scheme. The translational energy of the ions, Elab, was varied from 0.1 eV to approximately 30 eV. A small activation barrier impedes the reaction. Vibronic state preparation of the nitrogen ion is influential on the nature of the energy surface—N+2+H2 or H+2+N2—along which the H atom transfer proceeds. Calculations of model potential energy surfaces suggest that the reaction pathway must involve several exoergic and endoergic channels which open successively as the collision energy increases. A purely collision determined cross section—as would be evidenced by the E-1/2 dependence formulated in the Langevin–Gioumousis–Stevenson model—is observed only within a narrow window of kinetic energies. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This paper reports the results of two related experiments: (A) The state-to-state rotational transition probabilities of N2(a 1Πg) in collisions with rare gas atoms (Ar or He) were measured by the technique of two-step multiphoton ionization. Results show that the selection rule antisymmetric–symmetric is obeyed. The transition probability drops rapidly with increasing |ΔJ|. A propensity rule related to the Π+ or Π- symmetry conservation of the electronic wave function during the collision induced rotational transition holds. (B) The cross section for the rovibronic energy transfer between N2(1Πg) and N2(X 1Σ+g) is found to be ∼28 Å2. N2(a 1Πg) product populations show a Boltzmann-like distribution with a rotational temperature suggesting an equipartition of the available energy among the rotational and translational degrees of freedom of the products. A mechanism invoking an intermediate collision complex along with intermolecular electron exchange may explain the results. [ABSTRACT FROM AUTHOR]

The photoelectron spectra are reported from resonantly enhanced multiphoton ionization of N2 via the a 1Πg(v=10–14) states. Ionization from these levels is found to follow a (2+1) pathway resulting in N+2 X 2Σ+g(v+=0–4) ions. The observed branching ratios in the photoelectron spectra reveal a strong propensity for forming ground state ions in a single vibrational state. The results are explained qualitatively by favorable Franck–Condon overlap in the ionizing X 2Σ+g–a 1Πg transition. [ABSTRACT FROM AUTHOR]