State-Selective Electron Capture for keV He²⁺ Ions on Helium Collisions Studied by Recoil Momentum Spectroscopy

State-selective single electron capture cross sections are measured by recoil ion momentum spectroscopy technique for He²⁺ on He at 30keV incident energy. The cross sections for capture into ground and excited states are obtained and compared to classical model calculations as well as to the quantum mechanical calculations. The experimental results are in good agreement with quantum mechanical results.