LASER-BASED SYNTHESIS, DIAGNOSTICS, AND CONTROL OF SINGLE-WALLED CARBON NANOTUBES AND NANOHORNS FOR COMPOSITES AND BIOLOGICAL NANOVECTORS

Abstract

The controlled synthesis of nanoparticles and nanotubes utilizing lasers is described with applications in multifunctional composites and biological nanovectors. Lasers offer unique advantages for the synthesis of novel nanomaterials such as single-walled carbon nanotubes and single-walled carbon nanohorns, which form naturally within the laser vaporization plume under certain conditions. Time-resolved, laser spectroscopy and imaging is described to characterize and control the laser vaporization synthesis process. The growth conditions of single-walled carbon nanotubes by laser vaporization is described, and compared with that for single-walled carbon nanohorns. Optimization of the growth conditions is essential to produce nanomaterials which may be highly purified. This is contrasted with chemical vapor deposition of carbon nanotubes which are grown oriented from predeposited metal catalyst on substrates. Laser diagnostics are described which permit the first direct kinetics measurements of nanotube growth by chemical vapor deposition, understanding of the growth process, and control of nanotube length and wall number. Through these diagnostic techniques, both highly-purified loose nanomaterials or oriented nanotubes on substrates may be obtained to take advantage of the unique properties of nanomaterials as multifunctional nanocomposites and biological nanovectors.