Ion–molecule association reactions: A study of the temperature dependence of the reaction N+⋅2+N2+M → N+⋅4+M for M=N2, Ne, and He: Experiment and theory

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Abstract
The temperature dependence of the N+⋅2+N2 → N+⋅4 association has been investigated using a mass spectrometer source with coaxial electron entrance and ion exit apertures. The source resembles a miniature drift tube in that a small electric field is used to move the ions through the source. The effect of the field on the ion energy is discussed. Thermal reaction rate coefficients are obtained over the temperature range of 80 to 450 K, using He, Ne, and N2 as buffer gases. The experimental data reported here are compared with literature data as well as with the predictions of phase space theory calculations. Good agreement was found for the pure N2 system between the present results, previous experiments and theoretical calculations. Less good agreement was found between previous and present experiments when He was used as the buffer gas. In this case, the calculations tended to support the present results. The theoretical calculations also indicate a significant pressure dependence in the third‐order rate coefficient which may account at least in part for the discrepancy between results.