Charge-State Populations of 5- to 36-MeV Channeled Oxygen and Carbon Ions

Equilibrium and nonequilibrium charge-state distributions have been obtained for high-energy ions emerging from crystals. In a major channeling direction in silicon, the slower ions and those incident in low charge states emerge nearly at equilibrium, with a mean charge close to that in a random direction. High-energy channeled oxygen $8^{+}$ ions emerge far from equilibrium, indicating a capture cross section of less than 2× ${10}^{-19\mathrm{}}$ ${\mathrm{cm}}^2$.