Structural evolution of Au nanoclusters: From planar to cage to tubular motifs

The evolution of structural motifs of gold cluster anions, $\mathrm{Au}_{n}{}^{\ensuremath{-}}$, in the size range $n=11--24$ has been determined through a comparison of electron diffraction data with density functional calculations. The results provide clear evidence for a transformation from planar to three-dimensional structures in the range $n=12--14$, the development of cage structures for $n=16$ and 17, the appearance of a tetrahedral structure at $n=20$, and the emergence of a highly symmetric tubular structure for $n=24$.