Flow-drift technique for ion mobility and ion-molecule reaction rate constant measurements. III. Negative ion reactions of O− with CO, NO, H2, and D2

Abstract

A new combined flowing afterglow‐drift tube experimental appartus has been used to measure the reaction rate constants as a function of ion kinetic energy for the following negative ion reactions: $${\mathrm{O}}^{-}+\mathrm{CO}\to {\mathrm{CO}}_2\mathrm{+e,}$$ $${\mathrm{O}}^{-}+\mathrm{NO}\to {\mathrm{NO}}_2\mathrm{+e,}$$ $${\mathrm{O}}^{-}+{\mathrm{H}}_2\to {\mathrm{H}}_2\mathrm{O}\mathrm{+e}$$ $$\to {\mathrm{OH}}^{-}\mathrm{H},$$ $${\mathrm{O}}^{-}+{\mathrm{D}}_2\to {\mathrm{D}}_2\mathrm{O}\mathrm{+e}$$ $$\to {\mathrm{OD}}^{-}\mathrm{+D.}$$ Reaction (1) has been measured from thermal energy to ∼ 3 eV, (2) from thermal to ∼ 1.0 eV, (3) from thermal to ∼ 0.5 eV, and (4) from thermal to ∼ 0.8 eV. Reactions (1) and (2) are found to have rate constants that decrease by an order of magnitude with increasing ion kinetic energy, while Reactions (3) and (4) have total rate constants independent of energy. The channels (3b) and (4b) increase markedly with energy at the expense of the associative‐detachment channels (3a) and (4a). The present results are compared with existing available data on these reactions.