FIELD DESORPTION OF LITHIUM

Absolute appearance energies of field-desorbed Li+ ions were obtained from mass-to-charge resolved retarding potential analyses of Li+ emitt ed from the first and second Li layer on W(111). Activation energies f or Li+ field desorption were derived from desorption rate measurements . The field-independent binding energy of Li adatoms has been found fr om field-dependent Li+ appearance and activation energy values, indica ting a negligible field-induced charge transfer in the applied field r ange. We use the cluster embedded in jellium model, based on density-f unctional theory, to interpret the data by calculating local field enh ancements, surface potentials, and activation energies for Li field de sorption as a function of field strength and surface coverage as well as geometry.