X-ray spectroscopic and quantum–chemical study of carbon tubes produced in arc-discharge

High-resolution CKα spectra have been obtained for samples containing carbon cage particles, synthesized using the arc-discharge graphite evaporation technique. The X-ray fluorescence spectrum of particles from the inner part of the cathode deposit was found to differ from that of the soot collected on the chamber walls. The dependence of the spectral profile on the geometry was investigated using quantum–chemical calculations of carbon nanotube fragments with different helical pitches. The spectrum of multiwall particles agrees best with the theoretical spectra of zig-zag tubes. The agreement between the spectra of tubular particles in the soot and the theoretical results is best for single-wall armchair tube structures. These studies are complemented by calculations of the frontier orbitals of nanotube fragments.