Afterglow Studies of the Reactions He+, He(23S), and O+ with Vibrationally Excited N2

The following reactions have been measured as a function of N₂ vibrational temperature from 300°K to 6000°K: $$\mathrm{He}{}^{+}\mathrm{\hspace{0.17em}+\hspace{0.17em}}{\mathrm{N}}_2\to {\mathrm{N}}^{+}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{N}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{He}$$ $$\to {\mathrm{N}}_2^{+}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{He},$$ $$\mathrm{He}{\text{(2}}^3\mathrm{S)\hspace{0.17em}+\hspace{0.17em}}{\mathrm{N}}_2\to {\mathrm{N}}_2^{\mathrm{\hspace{0.17em}+}}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{He}\mathrm{\hspace{0.17em}+\hspace{0.17em}e,}$$ $${\mathrm{O}}^{+}\mathrm{\hspace{0.17em}+\hspace{0.17em}}{\mathrm{N}}_2\to {\mathrm{NO}}^{+}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{N}.$$ Reactions (1) and (3) are the first ion–molecule reactions to be measured as a function of vibrational temperature of the neutral. The rate constants for Reactions (1) and (2) are found to be insensitive to the N₂ vibrational temperature. Reaction (3) increases its rate constant by about a factor of 40 with increased N₂ vibrational temperature. The branching ratio (1a) to (1b) increases measurably with N₂ vibrational temperature.