Diagnostics of laser-produced plume under carbon nanotube growth conditions

Abstract

This paper presents diagnostic data obtained from the plume of a graphite composite target during carbon nanotube production by the double-pulse laser oven method.

Nucleation and growth of SWNT: TEM studies of the role of the catalyst

“…5(d)-(f)) is the nanotube growth which is likely to proceed by a progressive incorporation of carbon at the interface particle-nanotube. This scenario, which implies a root growth mechanism, is supported by the different TEM observations presented in Section 2.1, for the nucleation step at least, and by ab initio calculations [19], whereas in situ diagnostics performed in laser methods [10,12,14,36] and solar furnaces [37] provide information consistent with the first step. We discuss below in more details these different steps with a particular attention to the nucleation one which is the most crucial.…”

“…The presence of metal atomic vapours and of C 2 molecules is attested by the in situ diagnostics [10,12,14,37] done in continuous and pulsed vaporization reactors. As expected from thermodynamic data, carbon condenses first.…”

“…From an experimental point of view two types of methods are used. The structural determinations and chemical analyses of the synthesis products are made ex situ after the synthesis using local or global probes techniques (for a review see, e.g., [9]) whereas in situ diagnostics in evaporation-based synthesis reactors are now becoming available [10][11][12][13][14]. Among the techniques used in post synthesis analyses, transmission electron microscopy (TEM) plays a major role, since it is the only technique able to provide information in imaging, diffraction and chemical spectroscopy modes [8,9].…”

Efficient laser synthesis of single-walled carbon nanotubes through laser heating of the condensing vaporization plume

“…Small carbon fragment molecules such as C 2 have been observed in emission during the laser-synthesis of SWNT [12] and are thought to play a key role as carbon feedstock during nanotube growth. An argon ion laser was tested as the excitation laser in an attempt to excite C 2 through the Swan band transition and determine what influence electronically excited C 2 would have on SWNT synthesis.…”

The origin of the metal enrichment of carbon nanostructures produced by laser ablation of a carbon–nickel target

“…4, tends to produce the characteristic [17,28,29] and an intense, broad, 'blackbody-type' emission at short wavelength that has been attributed to C 3 [30] , small particulates [31,32], and electron bremsstrahlung. No evidence of either feature is found in the spectra of mixed carbon-nickel plumes under vacuum conditions.…”