Electron Impact Dissociative Excitation of Molecular Ions
The complex Kohn variational method, which has been very successful in treating the scattering of electrons from neutral polyatomic molecules,1 can also be used to study electron collisions with molecular ions. We have modified the method to deal with Coulomb boundary conditions. We have carried out ab initio calculations of the electron impact dissociation of H3 + via excitation of the two lowest (3E’, 1E’) excited electronic states, and HeH+ via excitation of the lowest 3Σ state.2,3 These calculations employed large 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 cross sections were found to be dominated by a series of sharp resonances, in apparent agreement with recent experimental findings 4,5 However, because the resonance states parallel their steeply repulsive ionic parent states, the final cross sections we obtained by averaging over the zero point vibrational motion of the symmetric stretch of the initial state, are structureless.
- 1.See, for example, T. N. Rescigno, in “Electronic and Atomic Collisions”, ed. W. R. MacGillivray, I. E. Mc Carthy, and M. C. Standage, (Adam Hilger, Bristol, 1992) pg.283, and references therein.Google Scholar