Differences in the adsorption of FePc on coinage metal surfaces

A study of the electronic and structural properties of iron phthalocyanine （FePc） molecules adsorbed on coinage metal surfaces Cu （100） and Cu （110） has been conducted by means of density functional theory calculations. The strength of the molecule-substrate interactions is interpreted in terms of the lateral adsorption geometry and the site specific electronic structure of the molecule. In the case of FePc on a （100）-oriented copper surface, the benzopyrrole leg is found to be oriented at an angle of 9°or 3°from the [01-1] substrate direction. Further, an upward bend in the molecular plane ranging from 7° to 10°is also observed; giving an almost buckled shape to the molecule. However, in the case of FePc on Cu （110）, neither a bend nor a sizable rotation is observed. From the knowledge of the principle structural and electronic properties, it is concluded that FePc-Cu （100） interaction is relatively stronger than FePc-Cu （110） interaction, which is further evidenced by the charge transfer, work function changes, changes in the shape of the adsorbed molecular orbitals, and the orbital shifts. Furthermore, density of states analysis shows that the valence band level shift is surface- and site-dependent.

A shortcut for determining growth mode

Thin and thick films of iron phthalocyanine （FePc） molecules are deposited on a Ag （110） surface. The nature of the FePc growth and the interaction with the substrate have been studied by X-ray photoelectron spectroscopy （XPS）. All of the core level spectra exhibit rigid shifts towards lower binding energies following the deposition of the organic films, each by a different magnitude. A greater change and a larger shift in the Fe2p level as compared to Cls core level reveals that the adsorbate interacts with the substrate mainly via the Fe atom, located at the center of the molecule. An increase/decrease in the intensity of C1 s/Ag3d level is found to be exponentially linked to the overlayer molecular coverage. Finally, the so- called growth/decay curve indicates that FePc thin films initially develop following the FM growth mode and then transform to SK mode, resulting in 3D island aggregation.

Adsorption of 1,3,5-Triphenylbenzene Molecules and Growth of Graphene Nanoflakes on Cu(100)Surface

Adsorption of 1,3,5-triphenylbenzene （TPB） molecules on Cu（100） surface is studied using ultraviolet photo- electron spectroscopy （UPS） and density functional theory （DFT） calculations. Researches on the bottom-up fabrication of graphene nanoflakes （GNFs） with TPB as a precursor on the Cu（100） surface are carried out based on UPS and DFT calculations. Three emission features d, e and f originating from the TPB molecules are located at 3.095, 7.326 and 9.349 eV below the Fermi level, respectively. With the increase of TPB coverage on the Cu（100） substrate, the work function decreases due to the formation of interfacial dipoles and charge （electron） rearrangement at the TPB/Cu（100） interface. Upon the formation of GNFs, five emission characteristic peaks of g, h, i, j and k originating from the GNFs are located at 1.100, 3.529, 6.984, 8.465 and 9.606eV below the Fermi level, respectively. Angle resolved ultraviolet photoelectron spectroscopy （ARUPS） and DFT calculations indicate that TPB molecules adopt a lying-down configuration with their molecular plane nearly parallel to the Cu（100） substrate at the monolayer stage. At the same time, the lying-down configuration for the GNFs on the Cu（100） surface is also unveiled by ARUPS and DFT calculations.