title: Optical spectroscopic studies of thermally coalesced single-walled carbon nanotubes.
abstract: Changes in the optical properties of thermally coalesced single-walled carbon nanotubes (SWCNTs) caused by heat treatment between 1300 and 2800 degrees C in argon, have been monitored using optical absorption and photoluminescence spectroscopy. For SWNTs heat treated at 1900 degrees C, we found a complete disapperance of small-diameter tubes (<1.0 nm) as well as the appearance of enlarged, defective tubes. The decreased sp2/sp3 ratio for tubes heat treated below 2100 degrees C suggests that adjacent small-diameter SWNTs transform into energetically stable larger-diameter SWNTs by the presence of structural non sp2 defects.
authors.affiliation: Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Muramatsu
authors.forename: Yong Jung
authors.initials: YJ
authors.lastname: Kim
authors.forename: Yoong Ahm
authors.initials: YA
authors.lastname: Kim
authors.forename: Takuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Morinobu
authors.initials: M
authors.lastname: Endo
authors.forename: Mauricio
authors.initials: M
authors.lastname: Terrones
authors.forename: Mildred S
authors.initials: MS
authors.lastname: Dresselhaus