Electron-impact dissociative excitation ofH3+

We report the results of an ab initio calculation of the electron-impact dissociation of ${\mathrm{H}}_3^{+}$ via excitation of the two lowest (${\mathrm{E}}^3$′,${\mathrm{E}}^1$′) excited electronic states, for electron energies between 15 eV, the threshold for excitation of the first electronic state, ${\mathrm{E}}^3$′, and 20.7 eV, corresponding to the excitation energy of the third excited electronic state, ${\mathrm{A}}_2^{1\mathrm{″}}$. The calculations, which were carried out using the complex Kohn variational method, employed extensive correlated target wave functions that accurately reproduced the energy levels and transition dipoles of the ground and excited states of the ion. All open channels were included explicitly in the scattering calculation. Closed-channel effects were included via an ab initio optical potential. The fixed-nuclei excitation cross sections were found to be dominated by a series of sharp resonance structures. However, when the cross sections are averaged over the Franck-Condon envelope of the ground vibrational state, these sharp features are no longer seen.