Electron transfer between He-like ions and He

Single- and double-electron-transfer cross sections have been measured for B³⁺, C⁴⁺, N⁵⁺, and O⁶⁺ in collision with He at velocities between 0.5 and 1.2×{}10⁸ cm/sec. The single-electron-capture cross sections peak near 15×{}10^-16 cm² for each case except C⁴⁺, where single capture is anomalously low. The double-capture cross sections are about 3×{}10^-16 cm², except for B³⁺, where the highest observed value is 1.5×{}10^-16 cm². These measurements for B³⁺ and C⁴⁺ compare well with existing experiments and theory, except for C⁴⁺ single capture. Within the narrow range tested, C⁴⁺ and B³⁺ cross sections exhibit variation with velocity, but N⁵⁺ and O⁶⁺ cross sections remain constant.