Projectile-charge dependence of ionization-excitation of helium following collisions of MeV bare ions with Zp=1 to 6

State‐selective cross sections σ+*(nl) have been measured for ionization‐excitation of helium in collisions with fully stripped ions. The energies of the H+, Li3+, B5+, and C6+ were .83 MeV/u and 1.60 MeV/u. These relate to collision velocities of 5.8 and 8.0 a.u. Data for the Lyman series, He+(np→1s), have been measured by observation of the extreme ultra‐violet spectra in the 22 to 31 nm wavelength range. The 2p‐ 1s data is presented and analyzed in terms of a simple power law dependence on the projectile charge state, Zpn. For the two equivelocity series of cross sections the powers, n, derived from least squares fits to the data were 2.89±0.3 and 2.83±0.4.