Localized and Dispersive Electronic States at Ordered FePc and CoPc Chains on Au(110)

Iron and cobalt phthalocyanines assemble on the Au(110) surface lying parallel to the surface, as deduced bynear-edge X-ray absorption fine structure (NEXAFS) taken with linearly polarized radiation at the C and NK edges. The molecular chains, firmly anchored to the underlying metal surface, arrange in long-range orderedrows with a (5 × 3) symmetry along the [001] azimuthal direction at completion of the first single layer. Theinteraction process is mainly determined by the d orbitals associated to the central Fe and Co atoms, asobserved by valence band photoemission and NEXAFS at the Fe and Co L2,3 edges. The spin and orbitalconfiguration of the FePc and CoPc molecules is strongly influenced by the interface with a charge transferfrom the underlying metal to the out-of-plane empty states located at the Fe and Co centers of the molecules.This interaction process induces electronic states located at the interface, localized on the central metal atomsand close to the Fermi level (0.2 eV binding energy for FePc and 0.7 eV for CoPc) without energy dispersion,as deduced by angular-resolved photoemission. On the contrary, a delocalized state has been observed withdispersion along the molecular chains, mainly due to the overlapping of the π charge of the macrocyclesligands mediated by the Au substrate