Exciton fine structure in a single carbon nanotube revealed through spectral diffusion

Abstract

We studied the spectral diffusion and exciton fine structures of single-walled carbon nanotubes (SWNTs) by using single carbon nanotube spectroscopy. Two types of single nanotube photoluminescence (PL) spectra were observed at temperatures below 50 K, which are double peaks with spectral diffusion and a single peak without spectral diffusion. The spectral diffusion that occurs in the lower energy peak of the split PL spectrum is associated with the quantum-confined Stark effect. Our observations suggest that symmetry breaking caused by the strong local electric field enables us to observe the dark exciton state below the bright exciton state in single SWNTs.