Molecular-beam deflection measurements of the static electric polarizability per atom, α/N, are reported for sodium clusters up to N=40. The quantity α/N decreases from the atomic polarizability to approximately 150% of the bulk value, at N=40. Potassium-cluster polarizabilities follow closely the same pattern up to N=20. There is some correlation between the polarizabilities and previously observed electronic shell structure.

• Received 26 November 1984

DOI:https://doi.org/10.1103/PhysRevB.31.2539