Coverage-driven electronic decoupling of Fe-Phthalocyanine from a Ag(111) substrate
T. G. Gopakumar, T. Brumme, J. Kröger, C. Toher, G. Cuniberti, and R. Berndt
Journal of Physical Chemistry C 115, 12173 (2011)
Coverage-dependent structural and electronic properties of Fe-phthalocyanine (FePc) molecules adsorbed on Ag(111) have been investigated by scanning tunneling microscopy/spectroscopy and density functional calculations. While spectra of single FePc molecules are dominated by a broad signature of Fe dorbitals, spectra of molecules in an ordered superstructure resolve spectroscopic contributions from individual dz2 and dxz/dyz orbitals. Calculations suggest that an increased molecule-surface distance in the superstructure and a change of the Ag(111) surface electronic structure cause the spectral changes, which are consistent with a partial electronic decoupling of the molecules from the substrate. A progressive evolution toward a gap around the Fermi level is observed for molecules on the first and second molecular layer.