Coherent Lattice Vibrations in Carbon Nanotubes
  We have generated and detected the radial-breathing mode of coherent lattice vibrations in single-walled carbon nanotubes using ultrashort laser pulses. Because the band gap is a function of diameter, these diameter oscillations cause ultrafast band gap oscillations, modulating interband excitonic resonances at the phonon frequencies (3-9 THz). Excitation spectra show a large number of pronounced peaks, mapping out chirality distributions in great detail. 
Y. S. Lim, K. J. Yee, J. H. Kim, J. Shaver, E. H. Haroz, J. Kono, S.   K. Doorn, R. H. Hauge, R. E. Smalley