Optical properties of 0.4-nm single-wall carbon nanotubes aligned in channels of AlPO4-5 single crystals

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2004-05, Vol.78 (8), p.1121-1128
• Main Authors: LI, Z. M, LIU, H. J, YE, J. T, CHAN, C. T, TANG, Z. K
• Format: Article
• Language: English
• Subjects: Absorption spectra; Channels; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Density; Electronics; Exact sciences and technology; Lattice dynamics; Mathematical analysis; Nanotubes; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Phonons in low-dimensional structures and small particles; Physics; Single crystals; Single wall carbon nanotubes; Zeolites
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-003-2463-3

Single-walled carbon nanotubes (SWNTs) of 0.4 nm in diameter are produced inside channels of microporous zeolite single crystals. Three possible structures: (5,0), (4,2), and (3,3) contribute to three bands at 1.37, 2.1, and 3.1 eV in optical absorption spectra. The direct correspondence between chiralities and absorption bands is identified by density functional calculations. The resonant Raman spectrum shows the features that can be assigned to van Have singularities in calculated phonon density of states. In the low-frequency region, two peaks at 510 and 550 cm are attributed to the radial breathing modes (RBMs) of the (5,0) and (4,2) tubes. After removing the zeolite framework, the RBM frequencies downshift by {/content/5D0P3KKUTEXWV39J/xxlarge8764.gif}10 cm. The charge-transfer behavior in lithium-doped 0.4-nm SWNTs is investigated. The Raman peak at 1558 cm couples with the electronic continuum, and shows a Breit--Wigner--Fano line shape.