Excitation and decay of vibrational autodetaching states of ${\mathrm{N}}_2^{-}$ produced in collisions of ${\mathrm{H}}^{-}$ with ${\mathrm{N}}_2$

A significant perturbation in the energy distribution of electrons has been observed for collisions of ${\mathrm{H}}^{-}$ on ${\mathrm{N}}_2$. The spacings between the large oscillations in the 1- to 4-eV region of the ejected electron spectra have been measured at observation angles between 30° and 150° for impact of 35- to 10000-eV ${\mathrm{H}}^{-}$ on ${\mathrm{N}}_2$. A model is proposed which interprets these results in terms of the formation and decay of a series of vibrational autodetaching states of ${\mathrm{N}}_2^{-}$. Electron distributions calculated using a molecular model based on the Franck-Condon principle for the excitation of the ${\mathrm{N}}_2^{-}$ states and various possibilities for the decay are compared with the experimental results.