Asymmetry of resonance Raman profiles in semiconducting single-walled carbon nanotubes at the first excitonic transition

Carbon nanotubes are one-dimensional nanoscale systems with strongly pronounced chirality dependent opti-cal properties with multiple excitonic transitions. We investigated the high-energy G mode of semiconductingsingle walled nanotubes of different chiralities at first excitonic transition by applying resonant Raman spec-troscopy. The G mode intensity dependence on excitation energy yielded asymmetric resonance Ramanprofiles similar to ones we reported for the second excitonic transition. We found the scattering efficiency tobe strongest at the incoming Raman resonance. Still, the degree of asymmetry is different for the first andsecond transitions and the first transition profiles provide a narrower line shape due to longer exciton life-times. The overall scattering efficiency is up to a factor of 25 times more intense at first excitonic transition,compared to the second transition. The fifth-order perturbation theory, with implemented phonon scatteringpathways between excitonic states, excellently reproduced experimental data