Rate coefficients ⟨σv⟩ for O+H collision processes at 6000 K, plotted against the asymptotic energy difference between initial and final molecular states, ΔE. The data are shown for endothermic processes, i.e. excitation and ion-pair production. The initial states of the transition are colour-coded, and the processes leading to a final ionic state (ion-pair production) are circled. The points are from the LCAO model and the bars show the fluctuations.