On the polarization-dependent Raman spectra of aligned carbon nanotubes

We perform polarized Raman spectroscopy on aligned single-walled carbon nanotubes. This test system allows us to empirically address if resonant Raman scattering from on-axis dipole transitions follows a cos2 or a cos4 mosaic spread. We observe in the polar plots a clear cos4 dependence, in agreement with the equivalency of incoming and outgoing dipole transitions.