Abstract
We have investigated excitons in highly aligned single-walled carbon nanotubes (SWCNTs) through optical spectroscopy at low temperatures down to 1.5 K and high magnetic fields up to 55 T. SWCNT/polyacrylic acid films were stretched, giving SWCNTs that are highly aligned along the direction of stretch . Utilizing two well-defined measurement geometries, and , we provide unambiguous evidence that the photoluminescence energy and intensity are only sensitive to the -component parallel to the tube axis. A theoretical model of one-dimensional magnetoexcitons, based on exchange-split “bright” and “dark” exciton bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfully reproduces our observations and allows determination of the splitting between the two bands as for (6,5) SWCNTs.
- Received 3 June 2008
DOI:https://doi.org/10.1103/PhysRevB.78.081402
©2008 American Physical Society