Raman scattering capabilities to characterize the variation of single wall carbon nanotube (SWCNT) material are demonstrated in a parametric study of carbon nanotube production by a double-pulse laser oven process. The effect of various operating parameters on the production of carbon single wall nanotubes is estimated by characterizing the nanotube material using analytical techniques, including SEM, TEM, TGA, and Raman. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure flow rate, inner tube, and lower flow rates.
DURING THE LAST FEW YEARS, INTEREST HAS GROWN IN single-wall carbon nanotubes (SWCNTs) that can be produced by different processes, including the arc process, laser ablation process, chemical vapor deposition (CVD), and gas phase processes, such as carbon monoxide disproportionation. The laser ablation process developed by Rice University researchers is known to produce the highest percentage of SWCNTs and uses a double-pulse laser oven method. Normal operating conditions for this method utilize a green laser pulse (532 nm) followed by an infrared laser pulse (1064 nm) within a few nanoseconds to ablate a metal-containing graphite target. The target is located in a flow tube maintained in an oven at 1473K with argon flow of 100 sccm (standard cc per minute) at a pressure of 500 Torr. These conditions are important in optimizing the production of single-wall carbon nanotubes and can be used to scale up this process for large-scale commercial use. Previous work, mostly accomplished at Rice University, reported on the effect of oven temperature and briefly mentioned the possible effect of flow conditions. No systematic study had been done earlier.