Absolute partial cross sections for electron-impact ionization of H₂, N₂, and O₂ from threshold to 1000 eV

H. C. Straub, P. Renault, B. G. Lindsay, K. A. Smith, and R. F. Stebbings

Phys. Rev. A 54, 2146-2153 (1996)

Absolute partial cross sections from threshold to 1000 eV are reported for electron-impact ionization of H₂, N₂, and O₂. Data are presented for the production of H₂⁺ and H⁺ from H₂; the production of N₂⁺, N⁺ + N₂²⁺, and N²⁺ from N₂; and the production of O₂⁺, O⁺ + O₂²⁺, and O²⁺ from O₂. The product ions are mass analyzed with a time-of-flight mass spectrometer and detected with a position-sensitive detector whose output provides clear evidence that all energetic fragment ions are collected. The overall uncertainty in the absolute cross section values for singly charged parent ions is ±3.5% and is marginally higher for fragment ions. Previous cross section measurements are compared to the present results.