Electron Stripping of the Ground and Metastable State Helium Atoms in Helium, Nitrogen, Neon and Argon

The cross sections for one-electron stripping from the ground (σ 01 ) and metastable (σ 0 * 1 ) state helium atoms in helium, nitrogen, neon and argon have been measured by beam attenuation technique in the energy range from 13 to 50 keV. The cross sections σ 0 * 1 are larger than the cross sections σ 01 by a factor ranging from 10 in higher energy region to 20 in lower energy region in helium, nitrogen and argon. The corresponding factor in neon is about three. The present values of σ 0 * 1 are generally consistent with the results of Miers and Anderson for all gases investigated and with those of Gilbody et al. or their extrapolation except for neon. These are also in agreement with the results predicted theoretically by Bates et al. for neon and argon, but differ by a factor of about three from those of Bastien et al. for neon.