title: Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes
abstract: Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.
authors.affiliation: A. M. Rao and P. C. Eklund, Department of Physics and Astronomy and Center for Applied Energy Research, University of Kentucky, Lexington, KY 40506-0055, USA. E. Richter, K. A. Williams, S. Fang, K. R. Subbaswamy, Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055, USA. S. Bandow, Instrument Center, Institute for Molecular Science, Myodaiji, Okazaki 444, Japan. B. Chase, Dupont Experimental Station, E328163, P.O. Box 80328, Wilmington, DE 19880-0328, USA. M. Menon, Department of Physics and Astronomy and Center for Computational Sciences, University of Kentucky, Lexington, KY 40506-0055, USA. A. Thess and R. E. Smalley, Department of Chemistry, Rice University, Houston, TX 77005, USA. G. Dresselhaus, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. M. S. Dresselhaus, Department of Physics and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.initials: AM
authors.lastname: Rao
authors.initials: E
authors.lastname: Richter
authors.initials: S
authors.lastname: Bandow
authors.initials: B
authors.lastname: Chase
authors.initials: PC
authors.lastname: Eklund
authors.initials: KA
authors.lastname: Williams
authors.initials: S
authors.lastname: Fang
authors.initials: KR
authors.lastname: Subbaswamy
authors.initials: M
authors.lastname: Menon
authors.initials: A
authors.lastname: Thess
authors.initials: RE
authors.lastname: Smalley
authors.initials: G
authors.lastname: Dresselhaus
authors.initials: MS
authors.lastname: Dresselhaus