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We studied the electronic structure of nanostructured C films produced by ultrasonic cluster beam deposition with the intention to find out the bonding configuration of the C network and to determine the modification induced by transition metal cluster inclusion in the film. Exploiting the energy and spatial resolution of the Spectromicroscopy beamline at Elettra Synchrotron, we were able to follow...
This work involves the purification and isolation of arc-discharge and HiPco SWNTs using two different systems. The first involves the use of conjugated polymers such as PmPV to selectively isolate certain tubes. The second uses SWNT as templates for organic molecules such as terphenyl and anthracene. Improvements in the solubility of SWNTs are seen in both cases. Spectroscopic analyses indicate a...
This paper presents composites of polycarbonate (PC) having different amounts of multiwalled carbon nanotubes (MWNT). The composites were prepared by diluting a masterbatch of PC with 15 wt% MWNT using melt mixing in a DACA-Micro Compounder. Electrical resistivity measurements indicated percolation of MWNT between 1 and 1.5 wt%.Transmission electron microscopy (TEM) showed excellent dispersion of...
The main objective of this paper is to coat carbon multiwall nanotubes surface with TiO 2 as anatase in view of photocatalytic application for these nanocomposites. Carbon nanotubes were produced by catalytic decomposition of acetylene at 600 o C. The coating was performed by a sol-gel method using classical alkoxides as Ti(OEt) 4 and Ti(OPr i ) 4 and by hydrothermal...
Density functional theory is used to study carbon nanotubes grown inside a channel-like environment. Two types of systems were investigated: the zigzag nanotubes inside AlPO 4 -5 zeolite (AFI) channels and the achiral double-walled nanotubes. In this work the energetical stability of the selected systems is evaluated and the shifting and splitting of the phonons, especially the radial-breathing...
The structure of C 60 fullerene aqueous solution in dependence on the C 60 fullerene concentration in the water was studied and analyzed in detail using various spectroscopic techniques such as UV-VIS, Raman and IR-spectroscopy and small-angle neutron scattering (SANS). The obtained experimental results were confirmed by theoretical quantum-chemical calculations of the C...
Multi-walled carbon nanotubes (CNTs) were doped with B at the initial loading of 1 and 2.5 wt.% and their oxidation behaviors in both air and oxygen plasma were studied to assess the effects of substitutional B in carbon oxidation and examine the hypothesis that the preferential attack by atomic oxygen on basal plane is due to delocalized π-electrons. The effect of substitutional B on oxidation of...
The mechanical properties of multilayer amorphous carbon thin films, consisted of sequential sp 3 - and sp 2 -rich layers developed on c-Si, were investigated by nanoindentation. The total (~100 nm) and bilayer (14-45 nm) thickness, and the sp 3 and sp 2 carbon bonded content, were determined by spectroscopic ellipsometry. The continuous stiffness measurements technique...
The preferential sites for lithium doping in hydrogen-rich amorphous carbon materials are investigated by considering, as a model, a large polycyclic aromatic hydrocarbon (PAH): hexa-peri-hexabenzocoronene. Quantum-chemical calculations are carried out with B3LYP/6-31G * density functional theory to study the lowest energy configurations of the PAH doped with two lithium atoms. Infrared and...
Various properties (geometry, band structure and the totally symmetric vibrational modes) of small diameter single-walled carbon nanotubes (SWCNTs) were investigated by first principles density functional theory (DFT) calculations. We studied 40 different SWCNTs, including 14 chiral ones down to diameters of 0.3 nm. The behavior of small diameter tubes is significantly different from that of the usual,...
The computer simulation of the particle beam (electrons, one charged H and Li ions) induced fragmentation of C 60 fullerenes supported by MgO surface was carried out. In particular, we have developed the Monte Carlo simulation of the nuclear and electronic energy loses using the standard CASINO and TRIM packages for random targets. The radiation-induced defects generation, atomic excitation...
We report on the process of making graphite out of wood by catalytic carbonization. Two different types of microstructure were observed. One type being typical for graphitization of wood without the effect of a catalyst, the main characteristic being the typical fibrillar microstructure related back to the original cellulose morphology. A strong {0002} inner diffraction ring corresponding to the 0...
The process of carbon nanotubes and filaments production via catalytic decomposition of CO on SiO 2 -modified Co catalyst was investigated. It was demonstrated that variation in carbon nucleation conditions could be used for the production of different type of carbon deposits over the same catalyst. Carbon nucleation conditions were altered by varying reaction temperature and/or catalyst pretreatment...
Spontaneous decay process of an excited two-level atom placed inside or outside a single-wall carbon nanotube is analyzed for both weak and strong atom-radiation-field coupling regime. In the weak coupling regime, the effect of the nanotube surface has been demonstrated to dramatically increase the spontaneous decay rate--by 4-5 orders of magnitude compared with that of the same atom in vacuum. Such...
Comprehensive optical characterization of C 60 films on semiconductor substrates has been performed by means of ellipsometry, Raman and photoluminescence spectroscopy. The films have been prepared by the sublimation of C 60 in vacuum. The morphology of these films and the C 60 -substrate interaction were investigated by atomic force microscopy. Both flat and...
Thin films of C 60 fullerene were prepared by vacuum evaporation on cold substrates of thermally oxidized and bare silicon wafers. The effect of thermal annealing on C 60 films was investigated by means of Raman, atomic force microscopy and X-ray diffraction. It was found that the densification of C 60 films occurred at low temperature range whereas the change...
This work discusses new results obtained from analysis of Raman signal from isolated single wall carbon nanotubes. (1) Study of tangential (G band) modes frequency dependence on tube diameter and lineshape dependence on scattering polarization geometry shows clear observation of symmetry selection rules at the single nanotube level. Observation of E 2 phonon modes indicates Raman spectra coming...
Hydrogen separation properties in pore channels with the diameter comparable to CO 2 or less were investigated by using molecular sieving carbon membranes from polyimide. The accurate control of the pore channels in sub-nanometer scale gave membranes with quite high H 2 /CO selectivity on permeation, which can be used for hydrogen purification system. Adsorption and diffusion properties...
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