Observation of electronic and atomic shell effects in gold nanowires
  The formation of gold nanowires in vacuum at room temperature reveals a periodic spectrum of exceptionally stable diameters. This is identified as shell structure similar to that which was recently discovered for alkali metals at low temperatures. The gold nanowires present two competing `magic' series of stable diameters, one governed by electronic structure and the other by the atomic packing. 
A.I. Mares, A.F. Otte, L.G. Soukiassian, R.H.M. Smit, and J.M. van   Ruitenbeek