title: Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes.
abstract: The bright exciton emission of carbon nanotubes is appealing for optoelectronic devices and fundamental studies of light-matter interaction in one-dimensional nanostructures. However, to date, the photophysics of excitons in carbon nanotubes is largely affected by extrinsic effects. Here we perform time-resolved photoluminescence measurements over 14 orders of magnitude for ultra-clean carbon nanotubes bridging an air gap over pillar posts. Our measurements demonstrate a new regime of intrinsic exciton photophysics with prolonged spontaneous emission times up to T1=18 ns, about two orders of magnitude better than prior measurements and in agreement with values hypothesized by theorists about a decade ago. Furthermore, we establish for the first time exciton decoherence times of individual nanotubes in the time domain and find fourfold prolonged values up to T2=2.1 ps compared with ensemble measurements. These first observations motivate new discussions about the magnitude of the intrinsic dephasing mechanism while the prolonged exciton dynamics is promising for applications.
authors.affiliation: Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Sarpkaya
authors.forename: Zhengyi
authors.initials: Z
authors.lastname: Zhang
authors.forename: William
authors.initials: W
authors.lastname: Walden-Newman
authors.forename: Xuesi
authors.initials: X
authors.lastname: Wang
authors.forename: James
authors.initials: J
authors.lastname: Hone
authors.forename: Chee W
authors.initials: CW
authors.lastname: Wong
authors.forename: Stefan
authors.initials: S
authors.lastname: Strauf