A calculation is made of the total cross section for charge-exchange reactions of the type H+ + H(ls) → H + H+. Within the framework of first-order perturbation theory an exact summation over all bound states of the final atom has been performed; thus the cross section calculated is that for charge exchange to occur, irrespective of the state of the final neutral atom.Of interest is the fact that we can extract from this result the cross section σ(≥N) for forming excited states with principal quantum number ≥N. It is found that this cross section shows a marked resonance in the vicinity of ħ υ/e2 ≈ 1 where υ is the speed of the incoming ion relative to the initial atom. The magnitude of this cross section at resonance is approximately 32/N2 times the geometric cross section of the ground-state hydrogen atom.This result could be of considerable significance for the design and interpretation of experiments in which highly excited neutral atoms are injected into magnetic-mirror devices.
State-selective electron capture by Ar from H*() and H(): implications for charge exchange recombination spectroscopy diagnostics