Sodium cluster anions ${\mathrm{Na}}_n^{-}$ with $n=39–350$ have been studied by low temperature photoelectron spectroscopy and density functional theory (DFT). The highly structured experimental spectra are in excellent agreement with the electronic density of states (DOS) of the DFT lowest energy structures. Even for the largest sizes, a pronounced sensitivity of the DOS on fine geometric details could be observed, allowing for a reliable identification of a specific icosahedral growth motif. The intermediate sizes between the closed-shell Mackay clusters with 55, 147, and 309 atoms form by growth of overlayers, which often exhibit a twist deformation with respect to regular (Mackay-type) ones.

• Received 19 October 2006

DOI:https://doi.org/10.1103/PhysRevLett.98.043401