Excitation and ionization processes in slow collisions of ground-state and excited hydrogen atoms with protons

The collision dynamics in the ${\mathrm{H}}^{+}$+H system is considered at low relative velocities within the concept of hidden adiabatic energy crossings in the complex plane of internuclear distance. Detailed information is provided on the topology of all series of hidden crossings in this system which are involved in the transitions between the states with principal quantum numbers n≤4 and in the promotion of these states into the continuum. This information is used to perform cross-section calculations for the 1s→nl (n=2–4), n=2→n=3,4, and n=3→n=4 excitation transitions and for ionization from the n=1, 2, and 3 levels in the adiabatic energy region.