Fig. 2

State-averaged charge-transfer (CT) rate coefficients. Effective state-averaged CT reaction-rate coefficients as a function of Rb(\({}^{2}{P}_{3/2}\)) population for a \({{\rm{N}}}_{2}^{+}\) and b \({{\rm{O}}}_{2}^{+}\). The black dash-dotted lines show linear fits to the experimental data (green symbols). The orange solid line in b is a prediction of the effective rate coefficient for O\({}_{2}^{+}\) + Rb assuming Langevin interactions in reactions with Rb \({}^{2}{S}_{1/2}\) and additional ion-quadrupole interactions in reactions with Rb \({}^{2}{P}_{3/2}\). The blue solid line indicates the theoretical Langevin rate coefficient for \({{\rm{O}}}_{2}^{+}\) + Rb(\({}^{2}{S}_{1/2}\)). Error bars correspond to one standard error.