Ionization of molecular hydrogen

A general model, based on a theoretically calculated ionization oscillator strength and an experimentally determined excitation shape function, has been obtained for calculating the molecular hydrogen electron-impact ionization cross section of a transition between any discrete vibrational levels of the neutral X (1)Sigma(g)(+) state and ionic X (2)Sigma(g)(+) state. Specifically, the excitation shape function and ionization oscillator strength for transitions from the vi 0 level of the X(1)Sigma(g)(+) neutral state to the discrete levels of the X(2)Sigma(g)(+) ionic state are derived from analyzing several experimental measurements. The derived oscillator strength is found to be consistent with the 1994 photoabsorption measurements of Samson & Haddad and the 1977 theoretical cross sections of Flannery and coworkers. The derived excitation function, along with the oscillator strengths for transitions involving the v(i) > 0 level calculated from the data of Flannery and coworkers, permits an accurate calculation of the nondissociative cross sections of H-2 between any discrete vibrational levels over a wide energy range.