Band structure and inter-tube optical transitions in double-walled carbon nanotubes
arXiv:2005.13675 · doi:10.1103/PhysRevB.102.115426
Abstract
Usually, in optical spectra of double-walled carbon nanotubes (DWCNTs) weak van der Waals coupling between the layers leads only to a small shift of transition energies with respect to their values in pristine single-walled nanotubes. However, recent results have shown that the Rayleigh spectrum of the DWCNT (12,11)@(17,16) contains additional peaks. Using the tight binding approximation, we demonstrate that in specific DWCNTs the interlayer coupling can slightly modify the band structure of pristine nanotubes in such a way that the unconventional inter-tube electronic transitions become possible and additional peaks in the DWCNT optical spectrum appear. Using the known experimental data on 118 optical transitions in DWCNTs, in addition to the recently published case we reveal six more DWCNTs with inter-tube transitions and obtain geometrical selection rules permitting them. In few dozens of DWCNTs our approach yields the energies of electronic transitions close to the experimentally observed ones and may be useful for structural identification of this-type nanotubes.
11 pages, 3 figures. In the revised version we have added a new figure and a new section "Optical matrix elements for inter-tube transitions". Some parts of the manuscript have been moved to Appendix and Supplemental Material. The Article is accepted for publication in Physical Review B
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