Carbon nanotubes were synthesized over a series of Zn-containing Fe/alumina catalysts by chemical vapor deposition method at two reaction temperatures of 850 and 950 °C using methane as a carbon source. Catalysts were synthesized by keeping Fe concentration constant and varying Zn concentration to study the effects of Zn. The catalysts were characterized using X – ray powder diffraction and N2 ...

Using single-nanotube absorption microscopy, we measured the absorption cross section of (6,5) carbon nanotubes at their second-order optical transition. We obtained a value of 3.2 × 10(-17) cm(2)/C atom with a precision of 15% and an accuracy below 20%. This constitutes the first metrological investigation of the absorption cross section of chirality-identified nanotubes. Correlative absorptio...

Millimeter-long and well-aligned single-walled carbon nanotubes (SWNTs) have been produced on silica/silicon surfaces using the carbon monoxide chemical vapor deposition (CO-CVD) method. The orientation of the nanotube arrays can be well-controlled by the gas flow during the growth. The majority of the orientated SWNTs are straight and individual. The length of the nanotubes can be >2 mm for a ...

Y-junction carbon nanotubes were synthesized by arc discharge method from composite anode made of graphite powder, coal tar and alloy catalysts consisting of Fe, Ni, Co and S element. The synthesis of Y-junction carbon nanotubes was carried out in a mixture gas of 200 Torr Ar and 100 Torr H2. The as-synthesized Y-junction carbon nanotubes were examined by scanning electron microscopy (SEM), tra...

Spatially resolved Raman spectra of individual pristine suspended carbon nanotubes are observed under electrical heating. The Raman G+ and G- bands show unequal temperature profiles. The preferential heating is more pronounced in short nanotubes (2 microm) than in long nanotubes (5 microm). These results are understood in terms of the decay and thermalization of nonequilibrium phonons, revealin...

Optical properties of a series of finite sized hydrogenated carbon nanotubes with the smallest diameter of 4 A are studied systematically. Their absorption spectra are calculated with the localized-density-matrix method. The semiempirical MNDO parametric method 3 (PM3) Hamiltonian is employed. The finite optical gaps are predicted for the infinite long single-walled carbon nanotubes. Strong ani...

We demonstrate selective burnout of individual carbon nanotubes that are electronically resonant with the incident laser energy. Raman spectroscopy and atomic force microscopy are used to quantify the burnout of nanotubes. The threshold laser power for rapid burnout is found to occur between 0.4 and 0.9 W/lm. At lower laser powers of 80 mW/lm, the burnout depends linearly on time, over tens of ...

STATEMENT OF PROBLEM Most fractures of dentures occur during function, primarily because of the flexural fatigue of denture resins. PURPOSE The purpose of this study was to evaluate a polymethyl methacrylate denture base material modified with multiwalled carbon nanotubes in terms of fatigue resistance, flexural strength, and resilience. MATERIAL AND METHODS Denture resin specimens were fab...

While several approaches have been developed for sorting metallic (m) or semiconducting (s) single-walled carbon nanotubes (SWCNTs), the length of SWCNTs is limited within a micrometer, which restricts excellent electrical performances of SWCNTs for macro-scale applications. Here, we demonstrate a simple sorting method of centimetre-long aligned m- and s-SWCNTs. Ni particles were selectively an...

carbon dioxide is a major greenhouse gas that contributes to the global warming by more than %60. absorption has been widely used to treat high concentrations of co2 in synthesis gas production, hydrogen manufacturing, and natural gas processing. the most well established method to capture co2 is its removal by absorption into amine solutions in the presence of activators. in this research, co2...