Phthalocyanine (H2Pc) and its open-shell copper complex (CuPc) deposited on amorphous gold films have been studied by combining the outcomes of several synchrotron based spectroscopic tools (X-ray photoelectron spectroscopy, UV photoelectron spectroscopy and near-edge X-ray absorption fine structure, NEXAFS, spectroscopy) with those of density functional theory (DFT) calculations. The assignment of experimental evidence has been guided by the results of DFT numerical experiments carried out on isolated molecules. With specific reference to CuPc NEXAFS data collected at the N K-edge, they have been assigned by using the open-shell time-dependent DFT (TDDFT) in the framework of the zeroth order regular approximation (ZORA) scalar relativistic approach. The agreement between theory and experiment has been found to be satisfactory, thus indicating that the open-shell TDDFT (F. Wang and T. Ziegler, Mol. Phys., 2004, 102, 2585) may be used with some confidence to look into the X-ray absorption spectroscopy results pertinent to transition metal complexes. As far as the metal-ligand interaction is concerned, the combined use of NEXAFS spectroscopy and DFT outcomes ultimately testified the significant ionic contribution characterizing the bonding between the metal centre and the nitrogen atoms of the phthalocyanine coordinative pocket.

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We report the influence of the native amorphous SiO(2) shell on the cathodoluminescence emission of 3C-SiC/SiO(2) core/shell nanowires. A shell-induced enhancement of the SiC near-band-edge emission is observed and studied as a function of the silicon dioxide thickness. Since the diameter of the investigated SiC cores rules out any direct bandgap optical transitions due to confinement effects, this enhancement is ascribed to a carrier diffusion from the shell to the core, promoted by the alignment of the SiO(2) and SiC bands in a type I quantum well. An accurate correlation between the optical emission and structural and SiO(2)-SiC interface properties is also reported.

Silicon carbide (SiC) has unique chemical, physical, and mechanical properties. A factor strongly limiting SiC-based technologies is the high-temperature synthesis. In this work, we provide unprecedented experimental and theoretical evidence of 3C-SiC epitaxy on silicon at room temperature by using a buckminsterfullerene (C(60)) supersonic beam. Chemical processes, such as C(60) rupture, are activated at a precursor kinetic energy of 30-35 eV, far from thermodynamic equilibrium. This result paves the way for SiC synthesis on polymers or plastics that cannot withstand high temperatures.

High-kinetic energy impacts between inorganic surfaces and molecular beams seeded by organics represent a fundamental case study in materials science, most notably when they activate chemical-physical processes leading to nanocrystals growth. Here we demonstrate single-layer graphene synthesis on copper by C60 supersonic molecular beam (SuMBE) epitaxy at 645 °C, with the possibility of further reduction. Using a variety of electron spectroscopy and microscopy techniques, and first-principles simulations, we describe the chemical-physical mechanisms activated by SuMBE resulting in graphene growth. In particular, we find a crucial role of high-kinetic energy deposition in enhancing the organic/inorganic interface interaction, to control the cage openings and to improve the growing film quality. These results, while discussed in the specific case of graphene on copper, are potentially extendable to different metallic or semiconductor substrates and where lower processing temperature is desirable.Non-adiabatic molecular dynamics, Supersonic Molecular Beam Epitaxy.of in-plane carbon-carbon bonds (~ 7.4 eV per carbon atom) and of the graphene edge-metal substrate (~ 7 eV per carbon atom), and the reversibility of the growth dynamics. 1 However, high working temperatures, 3 even in excess of 1000 ºC, are needed in CVD to obtain good quality graphene layers and to initiate the desorption of the hydrogen atoms present in the hydrocarbon precursors. Furthermore, graphene growth by CVD may be critically affected by carbon solubility within the bulk and, finally, by the bond strength between carbon atoms and metal surface. Both these factors depend on process temperature conditions and, typically, CVD single-layer graphene exhibits several defects and polycrystalline structure. 4 Thus, much effort is currently devoted to a better understanding of the growth dynamics on substrate surfaces, to achieve large single-domain dimensions, optimal grain boundary matching and lower processing temperature. 4In this work, aiming at overcoming these issues, we demonstrate the possibility of inducing C60 cage unzipping by supersonic molecular beam epitaxy (SuMBE) on single-crystal (111) and polycrystalline copper surfaces. SuMBE application to graphene growth will be studied by investigating electronic and structural properties of the synthesized C60/Cu thin films and the role of thermal energy in single-layer graphene synthesis by a variety of in-situ and ex-situ experimental methods, such as electron and Raman spectroscopy and scanning microscopy techniques.Furthermore, first-principles simulations based on density functional theory (DFT) will be used: i) to simulate the C60 impact on Cu(111) surface at several kinetic energies (KE); ii) to show the 4 crucial role of non-adiabatic effects on cage breaking; iii) finally, to follow the long-time dynamics after cage rupture leading eventually to graphene formation. RESULTS AND DISCUSSION SuMBE deposition of C60 on copper, core and valence band characterization of the filmsSuMBE has been al...

We studied in detail the electronic properties of C44H10F20N4 (tetrakis(pentafluorophenyl)porphyrin, hereafter H2TPP(F)) via a combined study by photoelectron spectroscopy (PES) and density functional (DF) calculations, shedding new light on the role of the halide in this very interesting molecule for organic electronics. Valence and core levels have been investigated by means of PES on H2TPP(F) thin films deposited on the SiO2/Si(100) native oxide surface by supersonic molecular beam deposition (SuMBD). These experiments have been carefully interpreted on the basis of DF results pertaining to the isolated H2TPP(F). Non-relativistic calculations have been run to investigate valence states, whereas a two component relativistic approach within the zeroth-order regular approximation has been adopted to study core levels. The present results, in conjunction with those obtained previously on the H2TPP parent compound [M. Nardi, R. Verucchi, C. Corradi, M. Pola, M. Casarin, A. Vittadini and S. Iannotta, Phys. Chem. Chem. Phys., 2010, 12, 871], pave the way towards designing fully organic p–n junctions by using these macrocycles

The Hummers' method for graphite oxide (GO) preparation has been applied to graphite nanoplatelets, in order to achieve higher reaction yield and faster kinetics. Aqueous GO solutions have been used to produce uniform GO films on a polyethylene terephthalate substrate, generating graphene patterns in a controlled way (widths of a few tens of microns). The reduction of GO deposited on the polymeric substrate has been performed by using a Nd:YVO continuous-wave frequency-duplicated laser. Spectroscopic and diffractometric characterizations (FT-IR, visible-NIR, Raman, XPS, and XRD) have shown that the reduction process induced by the laser annealing technique is mainly due to dehydration of the GO layers. It has been obtained by means of a suitable laser optical apparatus, a controlled reduction of GO without damaging the substrate, and precise writing of micro-tracks that can be used as electrically and thermally conductive patterns.

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