Ionization of one-electron ions and capture by bare and one-electron ions of C, N, O, and F on He

Experimentally measured single-electron-transfer cross sections are presented for bare nuclei and one-electron ions of C, N, O, and F following collisions with a He-gas target in the energy range from ∼0.5-2.5 MeV / amu. Excellent agreement is found between the K-shell ionization cross sections (electron loss by one-electron ions) and a theoretical plane-wave-Born- approximation calculation without inclusion of Coulomb-deflection and binding-energy corrections. Comparisons are also made between the capture cross sections (electron gain) and previously measured total projectile x-ray cross sections. The ratio of the x-ray cross section to the total capture cross section is compared to the same ratio found through a Brinkman-Kramers (BK) calculation. The results of the comparison show that the single normalization constant for the capture to each state, which was used in the theoretical analysis of the x-ray cross section, is inadequate. In particular, the results show that the BK calculation underestimates the capture of the electron to the 1s and 2s states as compared to the higher, x-ray-emitting states. The total capture cross sections are also given as a function of EM (MeV / amu). For a given velocity the capture is dependent only upon the charge state of the incident ion. Also, the similar velocity dependence with average ratios of 1:0.68:0.44 for the charge-changing processes q→q-1 (q=8,7,and 6) correspond to a q3 dependence for the total cross section.