Dynamics of single-wall carbon nanotube synthesis by laser vaporization

Higher Order Chemistry Models in the CFD Simulation of Laser-Ablated Carbon Plumes

“…propagation that is far more in line with the experimental results observed by Puretzky et a1 [7] as shown in Fig. 2.…”

“…While both of these options yielded significant results, it was felt that the actual chemistry occurring in the carbon plume might have a greater affect on the plume than assumed. Indeed, in the earlier attempts at modeling the carbon plume, several thennophysical characteristics could never be matched to experimental observations of plume development -mainly the propagation distance of the plume itself [7]. In the present study, two additional chemistry models will be used to duplicate the previous studies simulations of the carbon plume.…”

Carbon Nanotubes – Imprinted Polymers: Hybrid Materials for Analytical Applications

“…The laser has sufficiently high energy density not to cleave the target into graphite particles but to vaporize it at the molecular level converting the graphite vapor into amorphous carbon as the starting material of SWNTs (Puretzky et al, 2000;Sen et al, 2000;Kokai et al, 2000). The annealing conditions of the amorphous carbon in the laser ablation method are more homogeneous than those of the arc-discharge method, in which the electrodes and the convection flow disturb the homogeneity of the temperature and flow rate (Zhao X. et al, 2003;Kanai et al, 2001).…”

Laser Interactions in Nanomaterials Synthesis

“…[25] As summarized in Figure 2.6, in situ imaging and spectroscopy studies of the ns-laser vaporization process revealed that (a) both carbon and metal are prinicpally in the form of atoms and molecules (C, C 2 , C 3 , Ni, Co) during the first 100 µs, when the plume of ejecta are within ~ 1 cm of the target, (b) that carbon forms clusters within 1 ms after laser vaporization, as the hot plasma cools, and that (c) Ni and Co form clusters later in time (1 ms < t < 2 ms) after laser ablation. [10,26] Through stop-growth experiments, where the plume was ejected from the hot oven after different growth periods (as revealed by imaging the plume via Rayleigh scattering shown in Fig. 2.5(e)), it was learned that only short SWNT "seeds" or nuclei had formed after 15 -20 ms of growth time.…”