Dissociation pathways and binding energies of lithium clusters from evaporation experiments

摘要

The unimolecular dissociation of energy rich lithium cluster ions shows that Li+ndissociate by sequential atom or dimer loss. The binding energies of Li+n(n=4ndash;42) generated in an evaporative ensemble are determined from unimolecular decay, within a well defined time window, and energy constraint. They present a sawtooth behavior vs cluster size less pronounced that it should be from a simple metal model. Oddndash;even alternation is superimposed on the sawtooth behavior, with odd sized cluster ions being more stable. Cohesive energies per atom of Li+nare deduced from these dissociation energies up ton=40 and from extended photohyphen;induced measurements up ton=95. Cohesive energies per atom of neutral clusters Linare derived by combining these ionic cohesive energies with the literature ionization potentials. The linearity of the neutral cluster cohesive energy vs the cluster surface to volume ratio permits a volume and a surface energy to be deduced. These values are compared to the bulk values.