Translational energy distributions and production mechanisms of the excited hydrogen atom (n = 3,4) produced in e-NH3 collisions

The Balmer α and β lines produced in e-NH₃ collisions have been measured precisely with the use of a Fabry-Perot interferometer. These lines are not polarized. The translational energy distributions of (H^*(n = 3,4) were determined from analysis of Doppler lineshapes and have five components; their peaks lie at 1, 3, 2, 4–5 and 8–12 eV. The excitation function H^*(n = 4)] has five thresholds at 22.5, 29.0, 33.3, 38.9 and 41.7 eV, and indicates that five dissociation processes contribute to the formation of H^*. Excitation to the Rydberg states converging to the (2a₁)^?1 state of NH₃⁺ is a major process for the formation of the first and the second components. Doubly excited Rydberg states play important roles in the dissociative excitation of NH₃.