Theoretical vibrational optical activity of chiral carbon nanoparticles: Fullerenes and carbon nanotubes

Abstract

A theoretical study of the first‐order resonance Raman optical activity (ROA) of a single‐walled carbon nanotube (SWCNT) is presented for the first time. Tight‐binding (TB) Raman and ROA scattering tensors are combined with precise first principles harmonic vibrational modes to obtain scattering intensities. This computational protocol for Raman and ROA spectra has been tested previously for chiral fullerenes, such as C76 [Nagy et al., J. Chem. Phys. 140, 044112 (2014)]. In the present study, this methodology is validated against density functional theory for the alternative case of C84. TB spectral shapes are found to be reliable to determine the absolute configuration of these cage like carbon structures with relatively small curvature. Utilizing the same method, Raman optical activity (ROA) intensities of the (6,5) SWCNT are calculated for three vibrational modes, radial breathing mode (RBM), G−, and G+. This tube exhibits approximately 5 orders of magnitude stronger ROA intensity compared to typical chiral molecules.

Resonance Raman Optical Activity of Single Walled Chiral Carbon Nanotubes

“…The strongest ROA signal is therefore expected from resonance with the first electronic transition. In accord with our previous prediction, 29 Magg et al 30 provide experimental evidence in the case of the (6,5) tube that SWCNTs can indeed exhibit remarkably strong Raman and ROA signals.…”

“…To the best of our knowledge, our previous work was the first theoretical study on SWCNT resonance ROA (RROA). 29 The recently reported study of Magg et al 30 is the first experiment in this line. Let us note for completeness that handedness of an individual SWCNT can also be investigated by scanning probe microscopy 31,32 and transmission electron microscopy.…”

“…29 Integration over the Brillouin zone is carried out numerically utilizing the Monkhorst-Pack scheme. 111 Figure 1) are split into two intervals to allow for better perceptibility of the less intense spectral bands in the smaller wavenumber region.…”

“…This computational protocol was validated by comparison to experimental Raman and accurate theoretical ROA spectra of common chiral fullerenes, such as C 76 and C 84 . 29,62 For systems with just slightly curved surface, like C 76 or C 84 , a tight-binding (TB) approximation at the π-electron level already gives qualitatively good spectra, which has been adopted for a periodic RROA computation previously. 29 The TB model of Ref.…”

“…These theoretical advancements were partly implied, but not dwelled on in our previous report. 29 Our novel applications are presented in Sect. 3, giving RROA spectra for six chiral SWCNTs with relatively small diameter.…”