Non resonant Raman spectra of homogeneous and inhomogeneous individual dimers of Single-walled Carbon Nanotubes (SWNTs)

Abstract

We study the effects of the coupling between single-walled carbon nanotubes (SWNTs) on the phonons in homogeneous (identical nanotubes) and inhomogeneous (different nanotubes) dimers of SWNTs. Bond polarization theory and the spectral moments method (SMM) are used to calculate the non-resonant Raman frequencies of the breathing-like modes (BLMs) and tangential-like ones (TLMs). The dependence of the phonons on different structural parameters such as diameter and chirality is investigated. We focus on the dependence of the so-called Breathing-Like Modes (BLMs) of dimers originating from the van der Waals coupling of the Radial Breathing Modes (RBMs) of each individual tube forming the dimer. On the other hand, the TLM of dimer is reported and discussed. Distinct behaviors of the TLM are evidenced. The calculated of spectra are compared with the few experimental Raman data obtained on individual dimers.