I&EC 214 |
| Katalin Kamarás1, Ferenc Borondics1, Hui Hu2, Mikhail E. Itkis3, Bin Zhao3, Robert C. Haddon4, Norbert M. Nemes5, John E. Fischer5, Zhihong Chen6, Maria Nikolou6, Andrew G. Rinzler6, and David B Tanner6. (1) Research Institute for Solid State Physics and Optics, P.O. Box 49, H 1525 Budapest, Hungary, (2) Departments of Chemistry and Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, (3) Department of Chemistry, University of California, Riverside, Riverside, CA 92521, (4) Departments of Chemistry and Chemical and Environmental Engineering, University of California at Riverside, Riverside, CA 92521-0403, (5) Laboratory on the Research of the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104, (6) Department of Physics, University of Florida, Gainesville, FL 32611 |
| We will report optical spectra in the full (FIR to UV) spectral range of several chemically modified SWNT's: doped by alkali metals or halogens and functionalized by addition of organic side groups on the double bonds, respectively. Changes are apparent in two spectral ranges, the far infrared (<1000 cm-1) and the NIR/VIS (6000 ? 17000 cm-1). Ionic doping by electrons or holes increases the FIR absorption, which can be followed by the shift of the plasma edge in reflectance or an increase of oscillator strength in absorption. In contrast, chemical functionalization causes a dramatic decrease in FIR absorption. Interband transitions between van Hove singularities lose intensity for both types of modification. The explanation for the different behavior lies in the different mechanisms: ionic doping injects charges into existing bands, whereas chemical functionalization fundamentally changes the band structure. FIR spectroscopy can also detect accidental ionic doping during purification. |
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Purification, Separation, and Characterization of Single-Walled Carbon Nanotubes (SWNT's) (sponsored by Advanced Materials & Nanotechnology Subdivision)
8:30 AM-12:15 PM, Wednesday, March 31, 2004 Marriott -- Orange County 2, Oral
Division of Industrial and Engineering Chemistry |