[Raman spectra of carbon nanotubes produced in different inert atmosphere and their pressures]

Carbon nanotubes are produced in two kinds of inert atmosphere at the pressure range of 11 to 92 kPa by arc discharge. First- and second-order Raman spectra of these samples have been measured and compared with each other. It is found that the position and bandwidth of the spectral lines depend on the kind of inert gases and their pressure. The Raman spectra of the nanotubes produced in argon gas are much more similar to that of polycrystalline graphite than those of the nanotubes produced in helium gas. The position and bandwidth of nanotubes Raman peaks also change with gas pressure in arc discharge. The Raman spectra of nanotubes produced in high pressure are much more like the graphite than those produced in lower pressure.