Spectroscopic signatures of spin-orbit coupling and free excitons in individual suspended carbon nanotubes
Résumé
We investigate the intrinsic magneto-optical properties of suspended single-walled carbon nanotubes of various chiralities, using a combination of spectrally and time-resolved spectroscopy of individual nanotubes at low temperature. This study elucidates the population and relaxation dynamics of the lowest-energy bright and dark singlet excitons that are mixed with the Aharonov-Bohm effect. The high-quality emission spectra reveal the residual oscillator strength of the dark exciton in zero field, as an optical signature of spin-orbit coupling. They also unveil an asymmetry in the bright exciton recombination line, attributed to the free nature of excitons in these unperturbed nanotubes.