Relation between peak structures of loss functions of single double-walled carbon nanotubes and interband transition energies
1 Electron Microscopy and Spectroscopy Group, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi
2 Department of Quantum Engineering, Nagoya University, Nagoya, Aichi and
3 Department of Physics, Tohoku University, Sendai, Miyagi, Japan
* To whom correspondence should be addressed. E-mail: y-sato{at}tagen.tohoku.ac.jp
Electron energy-loss spectra of single double-walled carbon nanotubes (DWCNTs) were compared with calculated joint density of states (jDOSs) obtained by a simple tight-binding (STB) and an extended tight-binding (ETB) method. From the comparisons, interband transition energies of ETB calculations show better agreement with peak positions of the experimental spectra than those of STB results. From a further comparison among calculated jDOS, real and imaginary parts of a dielectric function and a loss function Im[–1/
], it was confirmed that the peak energies in a spectrum of single DWCNTs are almost equal to those of the optical absorption spectrum 2.
Keywords carbon nanotubes, electron energy-loss spectroscopy, extended tight-binding calculation
Received 19 January 2008, accepted 17 June 2008