Fission of ionized alkali metal clusters

We study the symmetric fragmentation of ionized alkali clusters within a liquid-drop type model. The interplay of surface and Coulomb interactions leads to a stability condition against small deformations which depends on the ratioZ ²/N. For systems which are stable against small-amplitude oscillations we consider the possibility of large-amplitude modes eventually leading to fission and give in terms of the same quantity an estimate of the potential barrier for this fission channel.