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Amorphous carbon films free of hydrogen, deposited at room temperature by magnetron sputtering, were found to exhibit amorphous diamond character. The films were studied during deposition with real time and in situ spectroscopic ellipsometry (SE), from which the transparency, spectral dependence and composition were determined. Raman spectroscopy and X-ray reflectivity were also used to investigate...
Carbon nanotubes prepared by thermal decomposition of hydrocarbons on supported Co catalysts were investigated by STM in air. An interpretation of the STM images is proposed which accounts for specific distortions taking place while scanning three-dimensional objects whose dimensions are of the order of the curvature radius of the tip. These distortions have both geometric and electronic origins,...
Uniform diamond nucleation was achieved on a Si substrate over a large area using low pressure Electron Cyclotron Resonance microwave plasma chemical vapour deposition (CVD). Diamond nucleation density as high as 10 9 cm −2 was obtained using a CH4 He gas mixture when the substrate was positively biased with respect to the grounded chamber wall. Radical densities higher than those...
We propose a new form of carbon in which the atoms are arranged in a self-similar fashion. The hypothetical structure we consider is two-dimensional, having a fractal dimension df = 1 + log 2 log 3 ≈ 1.63 which we call the Davidene. Our results for the ground state geometries of the aggregate as a function of its size L indicate that the fractal cluster is stable, displaying a small “gap” (≈ 0.16...
Layers (~ 1 μm thick) of crooked carbon nanotubes 20–60 nm in diameter were obtained at 800 °C by pyrolysis of polyethylene in He atmosphere using a Ni plate as a catalytic substrate. They were identified by electron microscopy and electron diffraction. Tips of some tubes (~ 10 6 /cm 2 ) come out of the layer. We studied their field electron emission at 10 −9 torr vacuum. 1–10...
Closed fullerenes and nanotubes exhibiting high topologies from genus 5 to genus 21 are proposed. These structures (holey-balls and holey-tubes) possess only hexagonal and heptagonal (negative Gaussian curvature) rings of carbon with no dangling bonds and no pentagonal rings (no positive Gaussian curvature). Holey-balls and holey-tubes can be seen as finite zeolites since they present interconnected...
Diamond deposition by hot filament chemical vapour deposition (HFCVD) on DLC films prepared by laser ablation (5 nm < thickness < 20 nm) was studied by electron spectroscopics, including X-ray photoemission, Auger electron and electron loss spectroscopy directly connected to the HFCVD growth chamber. It is shown that, whatever the thickness and the annealing procedure, this carbon layer is removed...
Superhard and ultrahard phases of C 60 were synthesized by quenching at high pressures up to 13 GPa and high temperatures in the 300–2100 K range. The structures of the samples are discussed on the basis of X-ray and Raman spectra and electron microscopy data. The following physical properties of hard samples were studied: specific gravity; specific heat in the range 400–600 K; sound velocities;...
We describe the possibility to synthesize carbon nitride fine powder by laser pyrolysis of acetylene/nitrous oxide/ammonia mixtures. The powders were produced in a flow reactor by varying the relative concentrations of the sensitizers ( SF6 C2H4). The kinetics of the reaction was monitored by IR spectrophotometry of the exhaust gases. The powder crystallinity and bond structure was studied by X-ray...
We present 13 C MAS NMR measurements on the (C 59 N) 2 dimer. The room temperature NMR spectrum obtained by spinning the sample at 10 kHz shows a weak line at 90 ppm and a group of lines around 140 ppm. The simulation of the obtained spectra allows us to attribute the line at 90 ppm to the sp 3 carbons forming the expected interball single bond and the other lines to...
Several TEM techniques are used to characterise the local structure of low dimensional forms of carbon. HREM is particularly useful to describe the defect structure of thin films of diamond or fullerenes and C 60 –C 70 nanoclusters. A columnar form of graphite is analysed, mainly by electron diffraction which allowed us to propose a growth mechanism. Diffraction contrast dark field...
Quantum field chemistry (QFC) conception within the framework of the kinematic electrondensity waves formalism has been applied to the description of corpuscular electron swarming. Interspersed between atoms, electron corpuscular solitary waves organize some g-dimensional lattices. An energy of the corpuscular electron swarm per single electron was obtained. Estimates of proper equilibrium parameters...
Fairly pure hexaadducts of molecular weights ranging from 2 × 10 4 to 2 × 10 6 could be prepared by reacting polystyryllithium with C 60 in toluene. These star-shaped polymers, with a fullerene core, associate a low polymolecularity of the arms (I < 1.1) and a fairly good control of the functionality (6). Their behavior in toluene has been established using static and dynamic...
The irradiation-induced self-compression of carbon onions and their transformation to diamond crystals are studied in situ by electron energy loss spectroscopy at high specimen temperature in a high-voltage electron microscope. Plasmon peaks in the low-loss region and the carbon K edge with the near-edge fine structure exhibit characteristic changes during irradiation. The spectra show the increasing...
Carbon nitride thin films were deposited using an ArF excimer laser to ablate a target of 3,5 diamino 1,2,4 triazole (guanazole) in a reactive atmosphere of ammonia. Films were obtained at room temperature onto crystalline silicon and aluminium substrates. The dependence of the film properties on the ammonia pressure is reported. Films were characterized systematically by profilometry, Fourier Transform...
Carbon nitride (CN x ) thin films have been obtained by reactive magnetron sputtering in a pure N 2 discharge. The films have been characterised by Fourier transform infrared spectroscopy (IR), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy. A maximum value of N C = 0.5 has...
The first results of a novel laser induced pyrolysis (LIP) method for high yield production of fullerene and single walled nanotubes are reported. The pyrolysis process of graphite targets is carried out by means of a continuous CO 2 laser under a flowing argon atmosphere. The vaporization of the targets and the deposition of the generated soot take place in a vertical experimental set-up.
The phase transitions from an fcc to an orthorhombic structure were studied in detail for the AC 60 compounds. For moderately fast cooling (10 K min −1 , continuously) RbC 60 and KC 60 gave an overall identical spectra. In the frequency range of the former A g (2) pinch mode two components were detected. There origin could be explained assuming a Davidov splitting...
A number of different C 60 and C 70 fullerene monoderivatives were synthesized and doped with tetrakis(dimethylamino)ethylene (TDAE) and cobaltocene (Cp 2 Co) to create charge transfer complexes with the aim of finding novel magnetic materials based on fullerenes. In this work X-band electron spin resonance (ESR) measurements are presented together with characterization of...
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