title: Observation of excitons in one-dimensional metallic single-walled carbon nanotubes.
abstract: Excitons are generally believed not to exist in metals because of strong screening by free carriers. Here we demonstrate that excitonic states can in fact be produced in metallic systems of a one-dimensional character. Using metallic single-walled carbon nanotubes as a model system, we show both experimentally and theoretically that electron-hole pairs form tightly bound excitons. The exciton binding energy of 50 meV, deduced from optical absorption spectra of individual metallic nanotubes, significantly exceeds that of excitons in most bulk semiconductors and agrees well with ab initio theoretical predictions.
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: David J
authors.initials: DJ
authors.lastname: Cho
authors.forename: Brian
authors.initials: B
authors.lastname: Kessler
authors.forename: Jack
authors.initials: J
authors.lastname: Deslippe
authors.forename: P James
authors.initials: PJ
authors.lastname: Schuck
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie
authors.forename: Alex
authors.initials: A
authors.lastname: Zettl
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: Y Ron
authors.initials: YR
authors.lastname: Shen