Direct observation of dark excitons in individual carbon Nanotubes: Inhomogeneity in the exchange splitting

Ajit Srivastava, Han Htoon, Victor I. Klimov, Junichiro Kono

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We report the direct observation of spin-singlet dark excitons in individual single-walled carbon nanotubes through low-temperature micro-magneto-photoluminescence spectroscopy. A magnetic field (B) applied along the tube axis brightened the dark state, leading to the emergence of a new emission peak. The peak rapidly grew in intensity with increasing B at the expense of the originally dominated bright exciton peak and became dominant at B>3T. This behavior, universally observed for more than 50 tubes of different chiralities, can be quantitatively modeled by incorporating the Aharonov-Bohm effect and intervalley Coulomb mixing. The directly measured dark-bright splitting values were 1-4 meV for tube diameters 1.0-1.3 nm. Scatter in the splitting value emphasizes the role of the local environment surrounding a nanotube in determining its excitonic fine structure.

Original languageEnglish
Article number087402
JournalPhysical review letters
Issue number8
Publication statusPublished - Aug 21 2008


ASJC Scopus subject areas

  • Physics and Astronomy(all)

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