title: Transient grating measurements of excitonic dynamics in single-walled carbon nanotubes: The dark excitonic bottleneck.
abstract: Transient grating measurements affirm the excitonic model for single-walled carbon nanotubes (SWNT) by identifying the dark exciton (D) as the population relaxation bottleneck in semiconducting-SWNT (S-SWNT). The data allow the reconstruction of the kinetics of excitonic cascade and cooling, from band continuum to vibrational cooling in the ground electronic state. In S-SWNT, the intraband relaxation occurs in 40 fs, localization into the 2g exciton occurs in 50 fs, followed by the excitonic cascade: 2g --> 1u --> D --> 1g with time constants of 175 fs, 3 ps, 300 ps, respectively. Fluorescence from the 1u state is quenched by efficient population transfer to 1D dark exciton. In metallic tubes, cooling is completed on the time scale of 1 ps.
authors.affiliation: Department of Chemistry, University of California, Irvine, California 92697, USA.
authors.forename: H Ye
authors.initials: HY
authors.lastname: Seferyan
authors.forename: M B
authors.initials: MB
authors.lastname: Nasr
authors.forename: V
authors.initials: V
authors.lastname: Senekerimyan
authors.forename: R
authors.initials: R
authors.lastname: Zadoyan
authors.forename: P
authors.initials: P
authors.lastname: Collins
authors.forename: V A
authors.initials: VA
authors.lastname: Apkarian
mesh_terms: D003198:Computer Simulation; D004579:Electron Transport; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry*; D017785:Photons
chemical_list: D037742:Nanotubes, Carbon