Selective Synthesis of Sub-Nanometer Diameter Narrow Diameter Distribution SWNT

Sub-nanometer single walled carbon nanotubes (sub-nm SWNT) were synthesized at different temperatures (600-800 oC) using CoMn and CoCr based catalysts supported on MCM-41 silica templates. The state of the catalyst was investigated using X-Ray absorption, magnetization and reaction probes. The (n,m) indices of the sub-nm SWNT were determined from multiple excitation wavelength excitation Raman spectroscopy and photoluminescence measurements. The reaction conditions and catalyst formulation significantly affect the size and morphology of the catalyst. Reaction conditions and catalyst properties that favor the growth of semiconducting tubes whose diameters range from 0.48-0.68 nm will be discussed. Interestingly, dominant intermediate frequency modes were observed in the Raman spectra of sub-nm SWNT with diameters <0.7nm.