title: Defect-induced photoluminescence from dark excitonic states in individual single-walled carbon nanotubes.
abstract: We show that new low-energy photoluminescence (PL) bands can be created in the spectra of semiconducting single-walled carbon nanotubes by intense pulsed excitation. The new bands are attributed to PL from different nominally dark excitons that are "brightened" because of a defect-induced mixing of states with different parity and/or spin. Time-resolved PL studies on single nanotubes reveal a significant reduction of the bright exciton lifetime upon brightening of the dark excitons. The lowest-energy dark state has longer lifetimes and is not in thermal equilibrium with the bright state.
authors.affiliation: Dipartimento di Fisica E. Fermi, Università di Pisa and CNISM, Largo Pontecorvo 3, 56127 Pisa, Italy. Hayk@df.unipi.it
authors.forename: Hayk
authors.initials: H
authors.lastname: Harutyunyan
authors.forename: Tobias
authors.initials: T
authors.lastname: Gokus
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Green
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
authors.forename: Maria
authors.initials: M
authors.lastname: Allegrini
authors.forename: Achim
authors.initials: A
authors.lastname: Hartschuh