Self-assembly of extended polycyclic aromatic hydrocarbons on Cu(111)

The self-assembly of extended polycyclic aromatic hydrocarbons with different symmetries on the Cu(111) surfaces is studied by low-temperature scanning tunneling microscopy. All molecules show a commensurate monolayer structure, with significant structural differences with respect to the unit cell of the molecular lattice and the orientational ordering and these are dominated by molecule-substrate interactions, while molecule-molecule interactions determine the molecular packing density through steric repulsion.