title: Saturation of the photoluminescence at few-exciton levels in a single-walled carbon nanotube under ultrafast excitation.
abstract: Single air-suspended carbon nanotubes (length 2-5 microm) exhibit high optical quantum efficiency (7-20%) for low intensity resonant pumping. Under ultrafast excitation (150 fs), emission dramatically saturates at very low exciton numbers (2-6), which is attributed to highly efficient exciton-exciton annihilation over micron-length scales. Similar saturation behavior for 4 ps pulse excitation shows nonlinear absorption is not a contributing factor. The absorption cross sections (0.6-1.8x10(-17) cm2/atom) are determined by fitting to a stochastic model for exciton dynamics.
authors.affiliation: Department of Physics, Engineering Physics & Astronomy, Queen's University, Kingston, Ontario, K7L 3N6 Canada.
authors.forename: Y-F
authors.initials: YF
authors.lastname: Xiao
authors.forename: T Q
authors.initials: TQ
authors.lastname: Nhan
authors.forename: M W B
authors.initials: MW
authors.lastname: Wilson
authors.forename: James M
authors.initials: JM
authors.lastname: Fraser