“…5 and 6, the values of the "critical" collision energy at which the cross section vanishes depend on the particular excited state. For example, while the 1s 1/2 2p 1/2 : J = 1 state cannot be populated for T p =465, 587, and 766 MeV/u, the "critical" energies for the 1s 2 1/2 J = 0 → 1s 1/2 2p 3/2 : J = 1 transition are T p = 502, 632, and 820 MeV/u. This state dependence arises from the sensitivity of the total cross sections (as well as alignment parameters) to the transition energy ω = E f − E i , an effect that is also predicted for the hydrogen-like ions [cf.…”