We report absolute, state-selective cross sections for single-electron capture by He-like ions (${\mathrm{N}}^{5+}$, ${\mathrm{O}}^{6+}$, ${\mathrm{F}}^{7+}$, ${\mathrm{Ne}}^{8+}$) colliding on He which were determined by vuv photon-emission spectroscopy. The impact energy was varied between 0.05 and 2 keV ${\mathrm{amu}}^{\mathrm{-}1}$. The experimental data are compared with theoretical predictions based on the classical overbarrier model, the Landau-Zener model, and existing close-coupling calculations.

• Received 1 July 1993

DOI:https://doi.org/10.1103/PhysRevA.49.363