Dissociative attachment in optically pumped lithium molecules

Abstract

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\ensuremath{\sim}10 and v\ensuremath{\sim}13, states which lie above the attachment energy threshold, nor is there significant rotational variation between J\ensuremath{\sim}0 and J\ensuremath{\sim}20. The rate constant for dissociative attachment to these states for thermal electrons at \ensuremath{\sim}0.05 eV has been measured to be (2\ifmmode\pm\else\textpm\fi{}1)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}8}$ ${\mathrm{cm}}^{3}$ sec $^{\mathrm{\ensuremath{-}}1}$.