Electronic structure and arrangement of purified HiPco carbon nanotubes

The electronic structure of purified single-wall carbon nanotubes obtained from HiPco process has been probed by X-ray fluorescent spectroscopy. The CKa spectrum of the HiPco nanotubes revealed a significant enhancement of the high-energy maximum intensity compared with the graphite spectrum. Quantum chemical calculations of carbon nanotube models show the spectral variations could be caused by vacancies in the tube walls developed with the thermal and acid treatment of the sample.