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 Li₂(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^-8 cm³ sec ^-1.