Evidence of hollow golden cages

The fullerenes are the first "free-standing" elemental hollow cages identified by spectroscopy experiments and synthesized in the bulk. Here, we report experimental and theoretical evidence of hollow cages consisting of pure metal atoms, Au(n)(-) (n = 16-18); to our knowledge, free-standing metal hollow cages have not been previously detected in the laboratory. These hollow golden cages ("bucky gold") have an average diameter >5.5 A, which can easily accommodate one guest atom inside.