Rovibrationally enhanced dissociative electron attachment to molecular lithium

We have investigated the role played by initial rovibrational excitation of ${\mathrm{Li}}_2$ on the cross sections and rates for dissociative electron attachment to the molecule. For a given internal energy, the vibrational excitation enhances the attachment cross section more than the rotational excitation. The attachment cross sections and the attachment rates reach their maximum values when the process of dissociative attachment to rovibrationally excited molecules is still endoergic and, furthermore, these quantities stay close to their maximum values even when the process changes from being endoergic to exoergic. The upper bounds on the cross sections and the rates for dissociative electron attachment to ${\mathrm{Li}}_2$ are 12.8 A${\mathrm{̊}}^2$ and 1.25×${10}^{\mathrm{-}8}$ ${\mathrm{cm}}^3$ ${\mathrm{s}}^{\mathrm{-}1}$. At a fixed electron temperature, the kinetic energy of the negative ion formed by this process increases as the vibrational quantum number of the initial neutral molecule increases; the maximum kinetic energy of the ${\mathrm{Li}}^{\mathrm{-}}$ ion formed by attachment to the v=12 level of ${\mathrm{Li}}_2$ is 0.153 eV.