Web Release Date: June 2,
Magnetic Brightening of Carbon Nanotube Photoluminescence through Symmetry Breaking
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Department of Electrical & Computer Engineering and Carbon Nanotechnology Laboratory, Rice University, Houston, Texas 77005, Laboratoire National des Champs Magnétiques Pulsés, CNRS-INSA-UPS, 31400 Toulouse, France, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan, and IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598
Received February 1, 2007
Revised April 29, 2007
Abstract:
We report that symmetry breaking by a magnetic field can drastically increase the photoluminescence quantum yield of single-walled carbon nanotubes, by as much as a factor of 6, at low temperatures. To explain this we have developed a theoretical model based on field-dependent exciton band structure and the interplay of Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains our data as the first experimental observation of dark excitons 5-10 meV below the bright excitons.
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