Diameter dependence of Raman intensities for single-wall carbon nanotubes - art. no. 153401

The Raman-active radial breathing modes (RBM) and tangential modes (TM) of single wall carbon nanotubes (SWNT) are studied at fixed laser excitation e nergy 2.41 eV (514.5 nm). We focus on the striking diameter dependence of t he relative intensity of the TM and RBM between 0.9 and 2.1 nm, which displ ays a series of plateaux separated by well-defined minima around 1.35 and 0 .9 nm. This relates to the diameter dependence of allowed optical transitio ns (AOT) in SWNT. Diameters in the range 1-1.3 nm (above 1.4 nm) correspond to metallic (semiconducting) SWNT in resonance at 2.41 eV. The minima corr espond to out-of-resonance conditions for TM. The measurement of the diamet er dependence of the TM intensity for fixed laser energies is an alternativ e experimental way to plot the envelopes of the domains of AOT in SWNT.