The behavior of the disorder-induced D band in the Raman spectrum of single-wall carbon nanotubes (SWCNT's) was investigated both theoretically and experimentally. The measured maximum position of the D band for SWCNT bundles exhibits an oscillation superimposed on a linear shift, when the laser excitation energy Elaser varies in the range of 1.6-2.8 eV. We have shown theoretically by explicit integrations for the resonant Raman cross section that the D-band intensity of an isolated SWCNT has a sharp maximum when Elaser of either the incoming or the scattered photon matches a van Hove singularity in the joint density of states. This "resonance" must be considered in addition to the double resonance from a scattering by an impurity. Calculating the D band of a superposition of all the 114 SWCNT's within a given diameter range, both the shift and the oscillation in the experimentally observed spectra were reproduced.
|Number of pages||9|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Apr 15 2002|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics