| Abstract
| - The exciton binding energy serves as a critical criterion for identification of the nature of elementary excitations(neutral excitons versus a pair of charged carriers) in semiconductor materials. An exciton binding energy of0.41 eV is determined experimentally for a selected nanotube type, the (8,3) tube, confirming the excitonicnature of the elementary excitations. This determination is made from the energy difference between anelectron−hole continuum and its precursor exciton. The electron−hole continuum results from dissociationof excitons following extremely rapid exciton−exciton annihilation and possibly also ultrafast relaxation fromthe second to the first exciton states and is characterized by distinct spectroscopic and dynamic signatures.
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