Dissociative recombination ofNe2+molecular ions

Abstract

We present calculations of cross sections and rate coefficients for the dissociative recombination of $\mathrm{Ne}_{2}{}^{+}$, following collisions with low-energy electrons $(<1\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$. The resonance energies and autoionization widths for the doubly excited states of ${\mathrm{Ne}}_{2}$ lying between the ground and first excited states of the ion are computed from electron scattering calculations using the complex Kohn variational method. The dynamics of the dissociative recombination process is investigated using multichannel quantum defect theory. The calculated absolute rate coefficient at $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ is in good agreement with the existing measurement. The rate coefficient is found to decrease with electron temperature as ${T}^{\ensuremath{-}0.5}$ in the low-electron-temperature region $({T}_{e}<1000\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, where the process is dominated by the lowest $^{1,3}\ensuremath{\Sigma}_{g}^{+}$ dissociative states. For the high-temperature region $({T}_{e}>1000\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, where the contribution from remaining dissociative states (lowest $^{1,3}\ensuremath{\Sigma}_{u}^{+}$, $^{1,3}\ensuremath{\Pi}_{g}$, $^{1,3}\ensuremath{\Pi}_{u}$ and second resonance states of these symmetries) become more important, the rate coefficients decrease faster and eventually behave approximately as ${T}^{\ensuremath{-}1.5}$. We also present cross sections for competing electron-impact vibrational excitation and deexcitation of $\mathrm{Ne}_{2}{}^{+}$ obtained from the same calculations.