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Kono, Junichiro Zaric, Sasa 2009-06-03T21:09:00Z 2009-06-03T21:09:00Z 2007 Zaric, Sasa. "Optical spectroscopy of single-walled carbon nanotubes in high magnetic fields." (2007) Diss., Rice University. <a href="https://hdl.handle.net/1911/20674">https://hdl.handle.net/1911/20674</a>. https://hdl.handle.net/1911/20674 THESIS E.E. 2007 ZARIC Magnetic flux threading a single-walled carbon nanotube (SWNT) is predicted to influence its electronic structure through the Aharonov-Bohm (AB) effect, causing bandgap oscillations and absorption peaks splitting. In order to verify these predictions, near infrared (NIR) photoluminescence (PL) and visible-NIR absorption in the Voigt geometry were measured at room temperature in external magnetic field (B) up to 74 T. The used aqueous surfactant solubilized SWNT samples show excitonic interband absorption peaks coming from a range of nanotube chiralities present in the sample. At fields B > 30 T, PL peaks showed red shifts and changes in peak widths. Magneto-PL spectra were successfully simulated, demonstrating that the observed spectral changes can be understood in terms of magnetic alignment of SWNTs (due to their predicted anisotropy magnetic properties) and B dependent changes of the bandgap due to the AB effect. By using the measured B-induced nanotube alignment and the measured average length of nanotubes in the sample, we estimated SWNT magnetic anisotropy to be 1.4 x 10-5 emu/mol, consistent with theoretical predictions. At B > 55 T, clear absorption peak splittings were observed, with splitting rates of 1 meV/T in good agreement with theoretical predictions. Recent theory predicts a dark singlet exciton state (below the only bright singlet state) which brightens as B is applied. Our observation of two bright excitons at high B demonstrates that magnetic field is indeed capable of brightening dark excitons. 54 p. application/pdf eng Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder. Condensed matter physics Optics Optical spectroscopy of single-walled carbon nanotubes in high magnetic fields Thesis Text Electrical Engineering Engineering Rice University Doctoral Doctor of Philosophy open.access