(n,m) Assignments of Metallic Single-Walled Carbon Nanotubes by Raman Spectroscopy: The Importance of Electronic Raman Scattering

Abstract

In this work, we report an accurate and convenient method that can be used to assign the chirality of all metallic single-walled carbon nanotubes (M-SWNTs). This method is designed based on the electronic Raman scattering (ERS) features, which are resonantly enhanced at the corresponding excitonic transition energies (M and M). Using this method, we are able to accurately determine the electronic property M with the resolution of a vibrational Raman spectroscopy (∼0.3 meV), which is significantly higher than that of the electronic spectroscopies (∼3 meV). We use the M splitting value, which is found insensitive to environmental changes, as a universal criteria for (n,m) assignments in various environments. As an illustrative example, simply using a commercialized Raman spectrometer with two laser lines (1.959 and 2.330 eV), we are able to unambiguously assign 18 metallic chiralities with M in the 1.6-2.3 eV range in our samples. This method provides an accurate database of M's in a similar way as photoluminescence excitation spectroscopy does for S's. It can facilitate further systematic studies on the properties of M-SWNTs with defined chirality.

Electronic Raman Scattering in Suspended Semiconducting Carbon Nanotube

“…Therefore, we calculate an accurate value of S22 = 1.513 eV from the ERS feature for this particular nanotube. Together with what we have reported previously for M-SWNTs [19], we conclude that Eii with a high accuracy of ±1 meV can be directly obtained via the ERS features for all types of SWNTs, both metallic and semiconducting. agreements with our previous data on the ERS features of M-SWNTs [18].…”

Anisotropic Fano resonance in the Weyl semimetal candidate LaAlSi

“…The observation of BWF line shape suggests that the B 2 1 mode at 296 cm −1 contributes to the discrete state in the Fano resonance. On the other hand, the continuous spectrum in Fano resonance is typically provided by electronic scattering events known as the electronic Raman scattering (ERS), in which a photoexcited electron excites an electron-hole pair near the Fermi energy by the Coulomb interaction [27][28][29]. Thus, the appearance of the BWF line shape in Raman spectra is typically evidence that the observed material is a metal or a semimetal.…”

High-speed identification of suspended carbon nanotubes using Raman spectroscopy and deep learning

“…In addition, the position, width, and shape of the characteristic peaks in the Raman spectra are indicators of the molecular or crystalline structure, electronic properties, and the quality of the materials. In the case of CNTs, the so-called G band shape and resonant electronic Raman scattering are used to distinguish the type of CNT 8 – 10 . (see Supplementary information Fig.…”