title: Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra.
abstract: Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eiiand Eijoptical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eijoptical transition energies for any (n,m) species.
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wei
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Yomogida
authors.affiliation: Department of Physics, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Naomichi
authors.initials: N
authors.lastname: Sato
authors.affiliation: Department of Physics, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Riichiro
authors.initials: R
authors.lastname: Saito
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Kataura