Interlayer Interaction Effects on the G Modes in Double‐Walled Carbon Nanotubes With Different Electronic Configurations

We present experimental measurements of the features of G band in individual index‐identified free‐standing double‐walled carbon nanotubes. We examine Raman spectra of different electronic configurations of DWNTs, namely: SC@SC, SC@M, M@SC, M@M, and clearly establish that, as in SWNTs, the profile of LO G‐mode of each layer is broad (narrow) when the layer is metallic (semiconducting). The dependence of G‐modes on the diameter and inter‐layer distance in several SC@SC, SC@M, M@SC, M@M index‐identified DWNTs is reported. We find, that, independently of the metallic or semiconducting nature of the layers, the frequencies of LO and TO G‐mode of the inner and outer layers shift significantly with respect to the frequencies of the same modes in the constituent SWNTs.