A reexamination of the temperature dependence of the reaction of N⁺ with O₂

The rate constants for the reaction of N⁺ with O₂ have been measured as a function of temperature (200-1400K) in a selected ion flow tube (SIFT) and high temperature flowing afterglow (HTFA). The datasets agree well with each other and the rate constants exhibit little temperature dependence. This is in contrast to two previous experiments at elevated temperature that reported the rate constant increased with temperature up to 1000K. A small part of the difference is explained by the absence of a thermal transpiration correction in the original measurements. The new data implies that rotational and translational energy both have little influence on the reactivity. The equivalent nature of the two types of energy is expected from studies on other systems. Vibrational excitation appears to increase the rate constants to near collisional. The branching ratios measured in the SIFT are in good agreement with previous drift tube results and show that rotational and translational energy have little effect on the individual channels. Published by Elsevier Science B.V.