Dissociative attachment in optically pumped lithium molecules

Experimental observations of dissociative attachment in lithium are described. Using laser excitation of a supersonic lithium beam a population of metastable vibrationally excited lithium molecules has been created. A cold-electron population (0.13 eV) has been created by laser photoionization of lithium atoms, and the attachment of these electrons has been studied as a function of molecular state. The dissociative attachment rate constant does not vary significantly for ${\mathrm{Li}}_2$(X) between v∼10 and v∼13, states which lie above the attachment energy threshold, nor is there significant rotational variation between J∼0 and J∼20. The rate constant for dissociative attachment to these states for thermal electrons at ∼0.05 eV has been measured to be (2±1)×${10}^{\mathrm{-}8}$ ${\mathrm{cm}}^3$ sec ${}_{}{}^{\mathrm{-}1}{}_{}{}^{}$.