Anomalous two-peak G ′ -band Raman effect in one isolated single-wall carbon nanotube

Abstract

The resonant second-order G'-band Raman spectra of isolated single-wall carbon nanotubes (SWNTS) exhibit an interesting resonance phenomenon, whereby the G' band for some special (n,m) isolated SWNTS exhibits a two-peak structure, while for most SWNTs, the G'-band profile is a single Lorentzian peak. The two-peak phenomenon is explained by combining the double-resonance Raman effect, originally introduced for graphite, With the singular electronic structure of SWNTs, which is unique for a given (n,m) pair. Therefore, the G'-band profile is strongly dependent on the joint density of electronic states and provides useful information about the electronic structure and on the (n,m) assignment for the specific SWNT that is in resonance with the laser.