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Carbon nanotubes (CNT) and CNT-based active materials have been used to assemble the gas sensing unit of innovative platforms able to detect toxic atmospheres developing in confined workplaces. The main goal of the project was to realize a full-featured, operator-friendly safety detection and monitoring system based on multifunctional textiles nanotechnologies. The fabricated sensing platform consists of a multiple gas detector coupled with a specifically designed telecommunication infrastructure. The portable device, totally integrated in the workwear, offers several advantages over the conventional safety tools employed in industrial work activities. [ABSTRACT FROM AUTHOR]

We report that the enhancement in the contact resistance after pulse annealing using the electric-current-induced joule heating in Pd electrode make an effect on the field effect transistor (FET) characteristics consisted of an individual single walled carbon nanotube (SWNT). The SWNTs are deposited onto Pd electrode patterned on SiO2/Si substrate, through which the electrical currents flow for microseconds to achieve a low contact resistance by meting the Pd electrode for an instant. Here, the transport measurement was performed to an identical SWNT before and after the pulse annealing at various temperatures from room temperature to 4K. From the results, a decrease of barrier height was observed after applying the pulse annealing, but much smaller than the value estimated from an increase of source/drain current. Therefore, we suggest that the enhancement in the contact resistance after the pulse annealing results from an increase of the effective contact length, causing a higher transmission probability, rather than a decrease of the barrier height between SWNT and metal electrode. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Nitrogen doped single-walled carbon nanotubes has been prepared using the arc discharge method. The material contains in average more impurities like pristine (pure) carbon nanotube material produced with the same method. We have tested several purification methods like the oxidation in hot air. First tests have shown that nitrogen-doped nanotubes exhibit a higher reactivity and are therefore less inert towards oxidative purification methods used for carbon nanotubes. We want to present a new purification method. It is based on the oxidation of the carbon impurities, homogeneously dispersed in boiling tertrachloroethan under airflow. The purity of the sample was investigated using scanning electron microscopy and transmission electron microscopy. Another part will present the characterization of chemically modified nitrogen-doped nanotubes after purification and first steps of the functionalisation of the hetero-nanotube material. Because of already existing model systems with hetero fullerenes, we have chosen a ‘Mannich’-like reaction for the modification of nitrogen-doped nanotubes. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

For the first time, full transistor characteristics — both output and transfer characteristics — in field-effect transistor configuration have been recorded and TEM investigations have been performed on the same individual nanotubes and metallofullerene peapods. Usual approaches for combining transport and TEM on the same nanotube only allow for measuring the current voltage characteristics, but no gate dependence can be acquired. Applying our new method of underetching a Si/SiO2 substrate from the edge of a chip after the transport measurements, we can additionally get the transfer characteristics Isd(Vg), i.e. the gate response of the current, which provides crucial information about the electronic properties of the system investigated. After the transport measurements and the etching process the samples can be viewed in the TEM, which enables us to check, whether a contacted nanotube is really a single tube or a thin bundle and whether a tube is filled with fullerenes indeed. Gaining this additional structural information by TEM can significantly help to interpret electrical transport data correctly. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Liquid crystals are self-organizing anisotropic fluids. In this work the transfer of order from liquid crystals to single-wall carbon nanotubes embedded in them is exploited within the geometry of standard cells used for large-scale alignment of liquid crystals. Using Polarized Raman Spectroscopy the alignment of the SWCNTs along the common liquid crystal direction is unambiguously demonstrated through the analysis of the variation of the peak intensity of the nanotube Raman modes with respect to the polarization direction of the light. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A versatile procedure for combining high-resolution transmission electron microscopy (TEM) and electron diffraction with Raman spectroscopy and transport measurements on the very same nanotube is presented. For this we prepare free-standing structures on the corner of a substrate by electron beam lithography and an etching process. Further, this procedure makes possible a TEM quality control of nanotubes grown directly on the substrate. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

If endohedral metallofullerenes are inserted into a single-walled carbon nanotube (SWNT), a linear chain of metallofullerenes will form in the interior of the tube, the resulting structure is named metallofullerene peapod. C82 molecules each containing a single Dysprosium atom have been filled into single-walled carbon nanotubes. The success of filling was verified by transmission electron microscopy (TEM). Transport measurements in field-effect transistor configuration were performed on (Dy@C82)n@SWNT metallofullerene peapods. Several (Dy@C82)n@SWNT structures exhibit so-called ambipolar Isd(Vg) characteristics at 4.2 K. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present a method which allows to design almost arbitrary freestanding nanostructures by lithography in such a way that TEM investigations are possible in combination with various other measurements on the same carbon nanotube. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report that ohmic contact between individual single walled carbon nanotubes (SWNTs) and palladium (Pd) was formed by using the electric-current-induced joule heating in Pd electrode. The SWNTs are deposited onto Pd electrode patterned on SiO2/Si substrate, through which the electrical currents flow for microseconds. As a result, transport measurement exhibited a decrease in contact resistance between individual SWNT and Pd electrode from 3.3 MΩ to 176 kΩ at room temperature after joule heating induced by the electrical current. Atomic force microscopy also showed that a surface of Pd metal is smoothened in roughness after electrical current flowing, indicating metallic melting by joule heat. Therefore, we suggest the way to achieve a low contact resistance between SWNT and metal in field effect transistor at room temperature, instead of thermal annealing method at high temperature. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Different transparent conducting heterostructures as thin films on transparent plates have been obtained: a thin network of Carbon Nanotubes (CNT), 80% to 93% transparent and enough conducting to be used as anode, on which Polyaniline is deposited electrochemically. In order to obtain information about the possible interaction between CNT and the polymer, we analysed the Raman spectra, on these hetero-thin films obtained at different chemical and electrochemical conditions. To compare, we analysed by Raman spectroscopy self-standing CNT-Polyaniline films where polyaniline was electrochemically deposited on a thick network of CNT (bucky-paper). Electrical conductivity and optical transparency are measured: Polyaniline improves the conductivity by a factor from 2 to 3 for films where the transparency is 67%. The best transparency, 93% to 97%, is obtained with SOCl2 functionalized CNT thin networks. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Single wall carbon nanotubes produced by high pressure CO decomposition (HiPco process) were oxidized in air at 350 °C and treated by thionyl chloride to generate acylchloride groups. Subsequent coupling reactions were carried out with different amine molecules to form intertube junctions. Tripropylentetramine, 2,4,6-triaminopirimidine and 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole have been chosen as a molecular linker. The reaction products were characterized by XPS and Raman spectroscopy. Also electrical and mechanical properties of bucky papers prepared from chemically modified tubes were studied and are discussed. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Room temperature hydrogen sorption capacities of nanostructured carbon materials including single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), carbon nanohorns (CNH), activated carbon, carbon black and graphite are determined by the volumetric method. All carbon materials investigated, including the samples with high specific surface area as purified SWNTs prepared by the HiPco process and activated carbon, show a hydrogen storage capacity of less than 1 wt % at room temperature and pressures below 100 bar. [ABSTRACT FROM AUTHOR]