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Interface properties of cobalt(II) phthalocyanine (CoPc) and cobalt(II) hexadecafluoro-phthalocyanine (CoPcF16) to gold are investigated by photo-excited electron spectroscopies (X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and X-ray excited Auger electron spectroscopy (XAES)). It is shown that a bidirectional charge transfer determines the interface energetics for CoPc and CoPcF16 on Au. Combined XPS and XAES measurements allow for the separation of chemical shifts based on different local charges at the considered atom caused by polarization effects. This facilitates a detailed discussion of energetic shifts of core level spectra. The data allow the discussion of site-specific charge-transfer processes.

Core hole screening effects at organic/metal interfaces were studied by core level X-ray photoemission spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), and valence band ultraviolet photoemission spectroscopy (UPS). The comparison of energetic shifts in XPS and XAES enables the estimation of electronic relaxation energy (screening ability). Magnesium phthalocyanine (MgPc) and zinc phthalocyanine (ZnPc) evaporated on single crystalline Au(100) were used as model molecules. Two different features in the Mg KLL spectra can be clearly separated for (sub-)monolayer coverages, while only minor changes of the shape of Mg 1s are observed. Applying a dielectric continuum model, the major screening mechanism cannot be described sufficiently by polarization screening due to mirror charges, significant contributions by charge transfer screening have to be considered. In contrast, small screening effects in the bulk material can be explained by surface polarization. [ABSTRACT FROM AUTHOR]

The initial growth and interfacial electronic structure of perfluorinated iron phthalocyanine (FePcF16) on Cu(111) has been studied using X‐ray photoelectron spectroscopy (XPS) and polarization dependent X‐ray absorption spectroscopy (XAS). The planar molecules are oriented preferred flat lying on the substrate surface during the growth of the first layers while the tilt angle is increased in thicker films. A clear interaction at the interface is observed, involving both the central metal ion and the macrocycle. At monolayer coverages, the Fe2p spectrum shows an interface signal at 707.1 eV, while the C‐N component of the C1s spectrum is distinctly shifted with respect to the thicker films. In addition, the nitrogen atom is involved in the complex interaction (including charge transfer), best visible in the change of the shape in the π* resonance of N K edge spectra recorded from molecules at the interface. The initial growth and interfacial electronic structure of perfluorinated iron phthalocyanine (FePcF16) on Cu(111) is studied using X‐ray photoelectron spectroscopy (XPS) and polarization dependent X‐ray absorption spectroscopy (XAS). The interaction at the interface involves both the macrocycle (carbon and nitrogen) and the central metal ion of FePcF16. At higher coverages most likely the spin multiplicity of the Fe ion changes. [ABSTRACT FROM AUTHOR]

We review the interaction mechanism of transition metal phthalocyanines (TMPcs, TM = Mn, Fe, Co) on different metal substrates (Au, Ag, Ni). The interface to Ni is further modified by the introduction of a graphene intermediate layer. Although TMPcs are representatives for flat, π-conjugated carbon systems, their electronic properties are determined to a large extent by the central metal atom. We focus on the role of the central metal atom in interfacial charge transfer processes. On single crystalline metal substrates the molecules grow highly ordered with flat lying adsorption geometry. We focus on studies using photoexcited electron spectroscopies: photoemission and X-ray absorption spectroscopy (XAS or NEXAFS). The highly ordered growth of TMPcs supports the assignment of polarization dependent XAS features. Depending on both the substrate and the TMPc, the strength of the interaction reaches from weak physisorption to strong chemical interactions. The introduction of graphene buffer layers seems to be a promising route for the tuning of interface properties. [ABSTRACT FROM AUTHOR]