Relevance of the electron energy-loss spectroscopy for in situ studies of the growth mechanism\ud of copper phthalocyanine molecules on metal surfaces: Al(100)

摘要

Reflection electron energy-loss spectroscopy (EELS) in specular and off specular geometry has been employed\udto study the early stage of the copper phthalocyanine (CuPc) growth on Al(100) substrate. EEL\udspectroscopy has been a useful tool in order to study the electronic structure of molecular films also in the\udsubmonolayer regime. The electronic structure of the first deposited layer of CuPc is strongly influenced by\udcharge transfer from the Al substrate to the lowest unoccupied molecular orbital (LUMO). The strong\udmolecule-substrate interaction gives rise to a coverage dependent frequency shift of the Al surface plasmon.\udSuccessive layers have essentially the electronic structure of the molecular solid. Momentum resolved EELS\udmeasurements reveal that, in the case of the thicker film investigated (22 Å), the plane of the molecule is\udalmost perpendicular to the surface of the substrate.