Anisotropic optical absorption properties of single-walled carbon nanotubes (SWNTs) are determined from a vertically aligned SWNT film for 0.5-6 eV. Absorption peaks at 4.5 and 5.25 eV are found to exhibit remarkable polarization dependence and have relevance to optical properties of graphite. A method for determining a nematic order parameter for an aligned SWNT film based on the collinear absorption peak at 4.5 eV is presented, followed by the determination of the optical absorption cross section.

We have performed a systematic investigation of the influence of growth parameters on the synthesis of vertically aligned single-walled carbon nanotubes (VA-SWNTs) by the alcohol catalytic chemical vapor deposition (ACCVD) method. The growth process of the VA-SWNTs was monitored using an in situ optical absorbance technique and the effects of CVD temperature and ethanol pressure on the initial growth rate and the catalyst lifetime were investigated. We found that for a given CVD temperature, there is an optimum pressure at which VA-SWNT film growth is maximized, and this pressure increases with temperature. Below this optimum pressure, the growth reaction is first-order, with the arrival of ethanol to the catalyst being the rate-limiting step. The activation energy of the growth reaction was determined to be approximately 1.5 eV.The root-growth mechanism of VA-SWNTs synthesized by the alcohol CVD method was also confirmed by a two-stage growth process. Following a short growth period using normal ethanol, 13 C -labeled ethanol was introduced to continue the growth. The location of the 13 C was determined from resonance Raman spectra, confirming the root-growth mechanism.

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Single-walled carbon nanotubes with narrow diameter-distributions were synthesized by the catalytic CVD technique using fullerene, C 60 or C 70 , as the carbon source. Fe/Co bimetal particles supported with zeolite powder were exposed to fullerene vapor in a heated quartz tube furnace. With a precise control of fullerene vapor pressure, macroscopic amounts of SWNTs with relatively high quality were generated. The diameter distributions of SWNTs, estimated by an analysis of resonance Raman scattering using excitation wavelengths of 633, 514.5 and 488 nm, ranged between 0.8 to 1.1 nm. The narrowness of this distribution is ascribed to the formation of nanotube caps due to fullerene collisions. *Corresponding

Optical anistropy at optical communication wavelength was observed in films of vertically aligned single-walled carbon nanotubes (SWNTs). We report the control of both the polarization state and transmission of incoming light at 1550 nm by azimuthal and axial tilting of SWNT film about its aligned axis. The experiments reveal that the polarization state of light is susceptible to the azimuthal angle of the aligned direction of a SWNT having semiconductor characteristics and the intensity of the output beam after SWNT film shows cosine function dependence on the axial tilting angle.