IngentaConnect Synthesis of "Cactus" Top-Decorated Aligned Carbon Nanotubes and ...

Authors: Li, P.H.; Qu, Y.L.; Xu, X.J.; Zhu, Y.W.; Yu, T.; Chin, K.C.; Mi, J.; Gao, X.Y.; Lim, C.T.; Shen, Z.X.; Wee, A.T.S.; Ji, W.; Sow, C.H.

Source: Journal of Nanoscience and Nanotechnology, Volume 6, Number 4, April 2006 , pp. 990-995(6)

Publisher: American Scientific Publishers

Abstract:

We report a new morphology of "cactus" top-decorated aligned carbon nanotubes grown by the PECVD method using pure C₂H₂ gas. Unlike most previous reports, no additional carrier gas is used for pretreatment. Carbon nanotubes can still grow and maintain the tubular structure underneath the "cactus" tops. It is proposed that the H atoms produced by the dissociation of C₂H₂ activate the catalyst nanoparticles. Scanning electron microscopy (SEM) shows that the top "cactus" morphology is composed of a large quantity of small nanosheets. Transmission electron microscopy (TEM) reveals the amorphous carbon nature of these "cactus" structures. The formation of these "cactus" structures is possibly due to covalent absorption and reconstruction of carbon atoms on the broken graphite layers of nanotubes produced by the strong ion bombardment under plasma. The third-order optical nonlinearities and nonlinear dynamics are also investigated. The third-order nonlinear susceptibility magnitude |χ⁽³⁾| is found to be 2.2 × 10⁻¹¹ esu, and the relaxation process takes place in about 1.8 ps.

Keywords: CARBON NANOTUBES; CATALYST; NONLINEAR OPTICAL PROPERTIES

Document Type: Research article

DOI: 10.1166/jnn.2006.167

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Synthesis of "Cactus" Top-Decorated Aligned Carbon Nanotubes and Their Third-Order Nonlinear Optical Properties