During the fracture of nanocontacts gold spontaneously formed freely suspended chains of atoms, which was not observed for the iso-electronic noble metals Ag and Cu. Au also differs from Ag and Cu in forming reconstructions at its low-index surfaces. Using mechanically controllable break junctions it was shown that all the 5d metals that show similar reconstructions (Ir, Pt, Au) also formed chains of atoms, while both properties were absent in the 4d neighbour elements (Rh, Pd, Ag),
indicating a common origin for these two phenomena. A competition between s and d bonding was proposed as an explanation.
Common Origin for Surface Reconstruction and the Formation of Chains of Metal Atoms. R.H.M.Smit, C.Untiedt, A.I.Yanson, J.M.van Ruitenbeek: Physical Review Letters, 2001, 87, 266102 (4pp)