Isotope effect on band gap and radiative transitions properties of boron nitride nanotubes.
We have carried out an isotope study on the band gap and radiative transition spectra of boron nitride nanotubes (BNNTs) using both experimental and theoretical approaches. The direct band gap of BNNTs was determined at 5.38 eV, independent of the nanotube size and isotope substitution, by cathodoluminescences (CL) spectra. At lower energies, several radiative transitions were observed, and an isotope effect was revealed. In particular, we confirmed that the rich CL spectra between 3.0 and 4.2 eV reflect a phonon-electron coupling mechanism, which is characterized by a radiative transition at 4.09 eV. The frequency red shift and peak broadening due to isotopic effect have been observed. Our Fourier transform infrared spectra and density functional theory calculations suggest that those radiative transitions in BNNTs could be generated by a replacement of some nitrogen atoms with oxygen.
Han
Wei-Qiang
WQ
Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA. whan@bnl.gov
Yu
Hua-Gen
HG
Zhi
Chunyi
C
Wang
Jianbin
J
Liu
Zhenxian
Z
Sekiguchi
Takashi
T
Bando
Yoshio
Y
D001895:Boron / Q000737:chemistry; D001896:Boron Compounds / Q000737:chemistry*; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D007554:Isotopes / Q000737:chemistry; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013499:Surface Properties
D001896:Boron Compounds; D007554:Isotopes; D046911:Macromolecular Substances; C017282:boron nitride; D001895:Boron