The Double Resonance Raman Behavior of the Carbon Nanotube 2-D Mode Observed in Samples Enriched in a Single Chirality

Access to carbon nanotube samples enriched in single chiralities allows the observation of new photophysical behaviors obscured or difficult to demonstrate in mixed-chirality ensembles. Recent examples include the observation of strongly asymmetric G-band excitation profiles [1] and the unambiguous demonstration of Raman interference effects [2]. Likewise, the complex response expected for the CNT 2-D mode has not yet been clearly defined because of similar limitations. We present results on the dispersive and resonance behaviors of the 2-D mode obtained from samples enriched in a single chirality. The response will be discussed in the context of the interplay of dispersive effects and resonance with the E11 and E22 transitions. The results will be compared to simulations that include all relevant electronic and phonon bands tied to the double-resonance process. 1. J.G. Duque, et. al., ACS Nano, 5, 5233 (2011). 2. J. G. Duque, et. al., Phys. Rev. Lett., 108, 117404 (2012).