Ion-Rydberg atom collision cross sections

Abstract: Classical-trajectory Monte Carlo calculations have been performed for collisions of ions in charge states q=+1, +2, +5 and +10 with hydrogenic atoms in principal quantum levels n=1, 2, 5, 10 and 20. The collision velocity range investigated was 1<or=v/veor=2. For v/ve>or approximately=5, the sum of the charge-exchange (CEX) and impact ionization (ION) cross sections may be represented by sigma CEX+ION(a02)=6 pi n2q2/v2, where v is in atomic units. Analysis of the electronic levels produced after charge exchange by the ion indicates the capture proceeds into excited levels which tend to preserve the energy and orbital size of the initial Rydberg atom.