Trapping and moving metal atoms with a six-leg molecule

Putting to work a molecule able to collect and carry adatoms in a controlled way on a surface is a solution for fabricating atomic structures atom by atom. Investigations have shown that the interaction of an organic molecule with the surface of a metal can induce surface reconstruction down to the atomic scale(1-5). In this way, well-defined nanostructures such as chains of adatoms(2), atomic trenches(3,4) and metal-ligand compounds(5) have been formed. Moreover, the progress in manipulation techniques(6-10) induced by a scanning tunnelling microscope (STM) has opened up the possibility of studying artificially built molecular-metal atomic scale structures(11,12), and allowed the atom-by-atom doping of a single C-60 molecule by picking up K atoms(13). The present work goes a step further and combines STM manipulation techniques with the ability of a molecule to assemble an atomic nanostructure. We present a well-designed six-leg single hexa-t-butyl-hexaphenylbenzene (HB-HPB) molecule(14), which collects and carries up to six copper adatoms on a Cu(111) surface when manipulated with a STM tip. The 'HB-HPB-Cu atoms' complex can be further manipulated, bringing its Cu freight to a predetermined position on the surface where the metal atoms can finally be released.