Effect of water on resonant Raman spectroscopy of closed single-walled carbon nanotubes

Tunable Raman excitation spectroscopy with 1.55-1.77 eV laser energies was used to map the second van Hove singularities of semiconducting single-walled carbon nanotubes ropes in air and immersed in water. The optical transitions are assigned to different (n,m) tubes using a correlation of the diameter and radial breathing mode (RBM) in the Raman spectrum. The resonance energies are blue-shifted when the tubes are immersed in water and the shift depends on the chiral angle. In addition, the RBM frequencies are also blue-shifted upon immersion in water. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.