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| Title: | SPECTROSCOPY-BASED CHARACTERIZATION OF SINGLE WALL CARBON NANOTUBES | |
| DOI No: | 10.1142/9789812701879_0022 | |
| Source: | CLUSTERS AND NANO-ASSEMBLIES (pp 187-192) | |
| Author(s): | M. NAMKUNG
NASA Langley Research Center, Hampton, VA, USA 23681, USA J. S. NAMKUNG Naval Air Warfare Center, Patuxent River MD, USA 20670, USA B. WINCHESKI NASA Langley Research Center, Hampton, VA, USA 23681, USA J. SEO Hampton University, Hampton, VA, USA 23668, USA C. PARK National Institute of Aerospace, Hampton, VA, USA 23666, USA |
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| Abstract: | We present the initial results of our combined investigation of Raman scattering and optical absorption spectroscopy in a batch of single wall carbon nanotubes (SWNTs). The SWNT diameters first estimated from the four radial breathing mode (RBM) peaks using a simple relation of ωRBM = 248cm-1nm/dt(nm). The calculated diameter values are related to the optical absorption peaks through the expressions of first interband transition energies, i.e.,  for semiconducting and  for metallic SWNTs, respectively, where a is the carbon-carbon bond length (0.144 nm) and γ is the energy of overlapping electrons from nearest neighbor atoms, which is 2.9 eV for a SWNT. This analysis indicates that three RBM peaks are from semiconducting tubes, and the remaining one is from metallic tubes. The detailed analysis in the present study is focused on these three peaks of the first absorption band by determining the values of the representative (n,m) pairs. The first step of analysis is to construct a list of possible (n,m) pairs from the diameters calculated from the positions of the RBM peaks. The second step is to compute the first interband transition energy, E11, by substituting the constructed list of (n, m) into the expression of Reich and Thomsen, and Saito et al. Finally, the pairs with the energies closest to the experimental values are selected. |
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