Temperature dependent Raman spectra of isolated suspended single-walled carbon nanotubes
Ultralong isolated single-walled carbon nanotubes (SWCNTs) were synthesized on a SiO2/Mo mesh to fabricate long individual suspended SWCNT samples. We detected a delicately temperature dependent Raman RBM, G and G′ band frequency shift and linewidth increase of these SWCNTs in the range of 240–600 K. Softening of force constants induced redshift and the mechanism of corresponding spectra linewidth evolution with temperature was analysed and compared with previously reported theories and experimental results. Temperature coefficient differences between G− and G+ were not observed, but the linewidth broadening tendency differences of G− and G+ are obvious. In addition, temperature-dependent G′ band evolution, including both frequency red-shifting and FWHM increase has been reported here first. These results will facilitate understanding of the second order Raman scattering process in SWCNTs. Different temperature coefficients measured on suspended and supported parts of the same SWCNT verifies the substrate's influence.