Origin of the Breit-Wigner-Fano lineshape of the tangential G-band featureof metallic carbon nanotubes - art. no. 155414

A detailed line-shape analysis of the tangential G-band feature attributabl e to metallic single-walled carbon nanotubes is presented. Only two compone nts are needed to account for the entire C-band feature for metallic nanotu bes. The higher-frequency component has a Lorentzian line shape, and the lo wer one has a Breit-Wigner-Fano (BWF) line shape. Through comparisons of th e Raman tangential G-band spectra from three different diameter distributio ns of carbon nanotubes, we find that both the frequency and linewidth of th e BWF component are diameter dependent and show functional forms consistent with theory. The nanotube curvature is responsible for both the frequency differences between the two components of the characteristic metallic G-ban d spectrum and the BWF coupling of the lower-frequency component. Surface-e nhanced Raman spectroscopy studies provide supporting evidence that the pho non BWF coupling is to an electronic continuum.