In this paper we report spectral measurements of some relatively common substances but from the hazardous category (possibly to be used like explosives or their manipulation is dangerous) in view to create a database with spectra of such substances. THz transmission spectra of some pure materials and mixed ones are also introduced. The measurements were performed using a Time-Domain system that work in the range of 0.2-4.5 THz. We develop our algorithm to obtain maximum information from the measurement and to minimize the errors.
Because of their quantum-scale dimensions, nanoparticles exhibit properties different from those of the bulk. As a result
of their unique properties, numerous efforts have been made to disperse nanoparticles in polymers to enhance or modify
their structural and magnetic properties. A new in situ synthesis method was used to incorporate small iron nanoparticles
into a polyoxocarbosilane polymer matrix. Nano-magnetic iron-based composites were obtained by a one-step procedure
consisting of the IR laser co-pyrolysis of a sensitized (with ethylene) gaseous mixture containing gaseous iron
pentacarbonyl and hexamethyldisiloxane in argon. The simultaneously occurring formation of iron from iron
pentacarbonyl and that of organosilicon polymer from hexamethyldisiloxane yield iron nanoparticles surrounded by an
organosilicon polymer shell. The particles become superficially oxidized in the atmosphere. They were characterized by
Raman analysis, electron microscopy and magnetic measurements. The properties of the nanocomposite particles depend
on the experimental synthesis parameters such as flow rates of precursors, total pressure and laser power. Magnetization
curves, exchange bias <i>H</i>ex at <i>T</i> = 5 K and AC susceptibility were studied in the temperature range 5-400 K. It was found
that the nanocomposite should be in a ferromagnetic blocked state with a minor superparamagnetic contribution of the
Laser pyrolysis of a hydrocarbon-based mixture is a continuous method for the synthesis of soot-containing fullerene. In this synthesis process, the mechanism of fullerene formation and soot is the radical mechanism of the PAH formation. In the flames producing both fullerenes and soot, exactly forming carbon cages require particular types of reaction sequences. The fullerene concentrations are strongly correlated with those of PAHs in the flame. The equilibrium soot-PAHs-fullerene is dependent on experimental parameters. FTIR spectra of soot extracts and exhaust gases are discussed in the frame of this dependence.
Soots obtained by laser pyrolysis of different gaseous/vapor hydrocarbons were investigated. The morphology variation of carbon soot versus process parameters and nature of reactants was analyzed and discussed. The role of oxygen is essential in obtaining soot particles having considerable curved-layer content.
TiO<sub>2</sub> nano powder was prepared by laser pyrolysis of gas phase reactants. TiCl<sub>4</sub> (vapor) was used as titanium precursor. The crystalline structures and morphologies of the powder have been analyzed by transmission electron microscopy (TEM), selected area electron diffraction (SAD) and Raman spectrometry. The different characterization techniques suggest that a nano-crystalline mixture of anatase and rutile is obtained.
Iron-carbon composite nanopowders have been synthesized by the CO<sub>2</sub> laser pyrolysis of gas-phase reactants. The experimental device allows for a very low reaction time and a rapid freezing that creates nanoscale-condensed particles. Iron pentacarbonyl and ethylene-acetylene mixtures were used as iron and carbon precursors. In a two-steps experiment, the reaction products may present themselves as iron-based nanoparticles dispersed in a carbon matrix. By a careful control of experimental parameters and radiation geometries we demonstrate the feasibility of an efficient and well-controlled, single-step technique for the production of iron-based nano-cores embedded in carbon layers. Highly dispersed nanoparticles, narrow size distributions and particles with about 4.5 - 6 nm mean diameters were obtained. Electron microscopy and Raman spectroscopy were used in order to analyze the structure and composition of the obtained nanopowders as well as their Soxhlet residue.