title: X-ray absorption near edge structure study of BN nanotubes and nanothorns.
abstract: Two boron nitride (BN) nanostructures, the bamboo-like nanotubes and nanothorns where the nanosize h-BN layers are randomly stacked looking like thorns, were synthesized selectively via thermal chemical vapor deposition of B/B(2)O(3) under the NH(3) flow at 1200 degrees C. Electron energy-loss spectroscopy reveals the N-rich h-BN layers with a ratio of B/N = 0.75-0.85. Angle-resolved X-ray absorption near edge structure of these two N-rich nanostructures has been compared with that of h-BN microcrystals. The pi transition in the N K-edge shifts to the lower energy by 0.8-1.0 eV from that of h-BN microcrystals, and the second-order signals of N 1s electrons become significant. We suggest that the N enrichment would decrease the band gap of nanostructures from that of h-BN microcrystals. The Raman spectrum shows the peak broadening due to the defects of N-rich h-BN layers.
authors.affiliation: Department of Chemistry, Korea University, Jochiwon 339-700, Korea.
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Choi
authors.forename: Seung Yong
authors.initials: SY
authors.lastname: Bae
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Jang
authors.forename: Jeunghee
authors.initials: J
authors.lastname: Park
authors.forename: Ha Jin
authors.initials: HJ
authors.lastname: Song
authors.forename: Hyun-Joon
authors.initials: HJ
authors.lastname: Shin