Near-infrared spectroscopic study and handedness discrimination of large-diameter single-walled carbon nanotubes

The optical properties of single-walled carbon nanotubes (SWNTs) offer unique opportunities for near-infrared (NIR) imaging and sensing applications, particularly in the NIR-II region (900–1700 nm). However, previous NIR studies have predominantly focused on small-diameter semiconducting SWNTs, leaving large-diameter semiconducting and metallic SWNTs largely unexplored. Herein, we employ NIR Rayleigh scattering spectroscopy to resolve 80 lower-order optical transitions in metallic and semiconducting SWNTs ( M 11 and S 22 , respectively), covering most of the NIR-II window (0.8–1.5 eV), from measuring more than 50 large-diameter SWNTs (1.5–3.5 nm). Together with the resonant Raman spectroscopy in the visible range, we significantly extend the previous Kataura plot into the NIR spectral region. Through detailed analysis of exciton resonance linewidths, we establish the first comprehensive dataset of exciton dephasing times for large-diameter SWNTs in the NIR spectral range, revealing decreased dephasing times with increasing exciton energies. We further achieve a generic and nondestructive handedness discrimination for large-diameter chiral SWNTs by utilizing preferential crystallographic alignment between chirality-identified SWNTs and hexagonal boron nitride (hBN), driven by high temperature annealing under high vacuum. This approach enables complete structural assignment of SWNTs and paves the way for constructing and investigating chiroptical and magneto-electrical devices based on SWNTs.