  We report on an optical method to directly measure electron-phonon coupling
in carbon nanotubes by correlating the first and second harmonic of the
resonant Raman excitation profile. The method is applicable to 1D and 0D
systems and is not limited to materials that exhibit photoluminescence.
Experimental results for electron-phonon coupling with the radial breathing
mode in 5 different nanotubes show coupling strengths from 3-11 meV, depending
on chirality. The results are in good agreement with the chirality and diameter
dependence calculated by Goupalov et al.
