Structure and electron states of Co-phthalocyanine interacting with the Cu(111) surface

We present a study of the growth and electronic properties of Co-Phthalocyanine(CoPc) molecular layers on Cu(111). Scanning tunnelling microscopy shows CoPc molecules adsorbing first at the Cu(111) step edges, lying “flat” i.e. parallel to the substrate. At monolayer saturation CoPc cover uniformly the Cu(111) surface with short range ordering. Angle dependent N 1s X-ray absorption spectroscopies (XAS) confirm the overall flat orientation. C 1s, N 1s, core-level photoemission and Co L3 edge XAS indicate selective participation of these atoms to the interface bonds. Angle resolved photoemission, up to 1ML, shows that the Cu(111) suface states undergo a shift to lower binding energies. This binding energy shift and the increase in the effective mass indicate a charge redistribution at CoPc/Cu(111) interface. At monolayer saturation the Cu(111) surface state is quenched and new molecular states appear at binding energies 0.9 eV and 1.37 eV.