NEXAFS and UPS studies of aligned single-walled carbon nanotubes on Si(100) substrates

ORAL

Abstract

We report near-edge absorption fine structure (NEXAFS) and ultraviolet photoemission spectroscopy (UPS) studies of aligned single-walled carbon nanotube films on Si(100) substrates. Polarization dependent data show very clear anisotropies due to the aligned nature of these films. We find different polarization dependent oscillator strengths for the $\pi ^{\ast }$-core exciton and the $\sigma ^{\ast }$-core exciton. From our data one can thus determine the orientation of the films using the NEXAFS spectra, with the intensity of the $\pi ^{\ast }$-core exciton at 284.4 eV showing a strong dependence on nanotube alignment with respect to the polarization of the incident radiation. At lower angles of incidence, the intensity of the $\pi ^{\ast }$ peak was higher for all orientations, which we attribute to the greater accessibility of the $\pi ^{\ast }$ orbitals. UPS spectra of the films showed little angular dependence and included features consistent with the total density of states of graphite. As a result of the nanotube curvature and the distribution of nanotube chiralities, the UPS spectra are similar to angle-integrated graphite spectra.

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Authors

  • Jack Rowe

  • R.F. Kelly

    SVT Associates, Department of Material Science and Engineering, Department of Chemistry, University of Florida, Florida International University, WebAssign, North Carolina State University, Broughton High School, Dept.~of Chemistry, Univ.~of Florida, Dept.~of Physics, Univ.~of Florida, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA, Center for Superconductivity Research, Dept. of Physics, University of Maryland, College Park, MD, 20742, USA, Dept. of Physics, University of Florida, 32611, USA, Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg, Germany, Physics \& Astronomy, UNC-CH, Chapel Hill, NC, University of North Carolina, Auburn University, University of Virginia, Tech. Univ. Eindhoven, University of Florida, Los Alamos National Labs, University of New Mexico, Advanced Materials Research Institute, University of New Orleans, New Orleans, LA, Department of Physics, University of Florida, UF, NHMFL, FSU / NHMFL, FSU, University of Arkansas, Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA, Dept. of Physics, University of Florida, Gainesville, FL 32611-8440, USA, Dept. Chemistry Florida State Univeristy, University of Brewen, Tohoku University, Okayama University, Dept of Chemistry, Florida State University, Dept. of Chemistry, Florida State University, National High Magnetic Field Laboratory, Tallahassee, FL, Laboratoire Lois Neel, Grenoble, France, Dept. of Chemistry, Texas A\&M University, Tsinghua Univ., INEL, JINR, Vanderbilt Univ./LBNL, Vanderbilt Univ., SVT Associates, Inc., Department of Chemical Engineering, University of Florida, Department of Materials Science and Engineering, University of Florida, Department of Electrical Engineering, National Central University, Taiwan, University of Miami, North Carolina Central University, University of Missouri Rolla, AB Millimetre, France, Thomas Keating Ltd., UK, Dept. of Physics, Univ. of Florida, Department of Material Science and Engineering University of Florida, Department of Chemistry University of Florida, Department of Chemical Eng. University of Florida, Naval Research Lab, Washington, DC, University of Rajshahi, LENIN All Russian Electrotechnical Institute, Moscow, Russia, Independent Researcher, Argentina

  • R.F. Kelly

    SVT Associates, Department of Material Science and Engineering, Department of Chemistry, University of Florida, Florida International University, WebAssign, North Carolina State University, Broughton High School, Dept.~of Chemistry, Univ.~of Florida, Dept.~of Physics, Univ.~of Florida, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA, Center for Superconductivity Research, Dept. of Physics, University of Maryland, College Park, MD, 20742, USA, Dept. of Physics, University of Florida, 32611, USA, Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg, Germany, Physics \& Astronomy, UNC-CH, Chapel Hill, NC, University of North Carolina, Auburn University, University of Virginia, Tech. Univ. Eindhoven, University of Florida, Los Alamos National Labs, University of New Mexico, Advanced Materials Research Institute, University of New Orleans, New Orleans, LA, Department of Physics, University of Florida, UF, NHMFL, FSU / NHMFL, FSU, University of Arkansas, Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA, Dept. of Physics, University of Florida, Gainesville, FL 32611-8440, USA, Dept. Chemistry Florida State Univeristy, University of Brewen, Tohoku University, Okayama University, Dept of Chemistry, Florida State University, Dept. of Chemistry, Florida State University, National High Magnetic Field Laboratory, Tallahassee, FL, Laboratoire Lois Neel, Grenoble, France, Dept. of Chemistry, Texas A\&M University, Tsinghua Univ., INEL, JINR, Vanderbilt Univ./LBNL, Vanderbilt Univ., SVT Associates, Inc., Department of Chemical Engineering, University of Florida, Department of Materials Science and Engineering, University of Florida, Department of Electrical Engineering, National Central University, Taiwan, University of Miami, North Carolina Central University, University of Missouri Rolla, AB Millimetre, France, Thomas Keating Ltd., UK, Dept. of Physics, Univ. of Florida, Department of Material Science and Engineering University of Florida, Department of Chemistry University of Florida, Department of Chemical Eng. University of Florida, Naval Research Lab, Washington, DC, University of Rajshahi, LENIN All Russian Electrotechnical Institute, Moscow, Russia, Independent Researcher, Argentina

  • Les Fleming

    NC State University

  • Marc Ulrich

    US Army Research Office