Sodium cluster ionization potentials revisited : higher resolution measurements for Nax (x<23) and their relation to bonding models

Controversy regarding the interpretation of ionisation efficiency measurements obtained for alkali clusters has provided impetus for higher-resolution studies (3.3 nm). The new data presented here cover the full range of cluster sizes Nax, x < 23. We discuss methods of assigning ionisation potentials and compare the resulting numbers with predictions from various model calculation