Spectroscopic Characteristics of Differently Produced Single-Walled Carbon Nanotubes

Four differently produced single-walled carbon nanotube (SWNT) materials (by arc discharge, HiPco, laser ablation, and CoMoCat method) with diameters ranging from 0.7 to 2.8 nm were investigated by using multiple characterization techniques, including Raman scattering, optical absorption, X-ray absorption near edge structure, along with X-ray photoemission. The vibrational spectroscopies revealed that the diameter distribution and the compositions of metallic and semiconducting tubes of the SWNT materials are strongly affected by the synthesis methods. Similar sp(2) hybridization of carbon in the SWNT structure oxygenated can be found but different surface functionalities arc introduced while the tubes are processed. All SWNTs exhibited stronger plasmon resonance excitations, lower electron binding energy compared to graphite. These SWNT materials also exhibit different valence band X-ray photoemission features which are affected by the nanotube diameter distribution and metallic/semiconducting composition.