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The propagation of azimuthally symmetric guided waves in multiwalled carbon nanotubes (MW-CNTs) was analyzed theoretically in the mid-infrared and the visible regimes. The MWCNTs were modeled as ensembles of concentric, cylindrical, conducting shells. Slightly attenuated guided waves and antenna resonances due to the edge effect exist for not-too-thick MWCNTs in the far-and mid-infrared regimes. Interband transitions hinder the propagation of guided waves and have a deleterious effect on the performance of a finite-length MWCNT as an antenna. Propagation of surface-plasmon waves along an MWCNT with a gold core was also analyzed. In the near-infrared and the visible regimes, the shells behave effectively as lossy dielectrics suppressing surface-plasmonwave propagation along the gold core.

Conformal metal oxide coatings on nanotubes by direct low temperature metal-organic pyrolysis in supercritical carbon dioxideUnderstanding the electromagnetic response of carbon nanotubes ͑CNTs͒ in the radio frequency range is very important for experimental development of therapeutic and diagnostic CNT applications, including selective thermolysis of cancer cells and thermoacoustic imaging. In this study, we present the theory of electromagnetic wave scattering by several finite length CNT configurations, including singlewall CNT's having a surfactant coating, CNT bundles, and multiwall CNTs. Absorption cross-sections of these structures in a conductive host region are theoretically studied in the radio frequency range. Strong local field enhancement due to edge effects is predicted to be inherent to metallic singlewall CNTs in the near-field zone, providing an additional mechanism of energy dissipation in a conductive host. Due to the screening effect the application of singlewall CNTs for the enhancement of energy dissipation is more effective than the application of multiwall CNTs or CNT bundles at the same mass fraction of CNT inclusions. The presence of a lossy dielectric ͑surfactant͒ coating can significantly increase the absorption cross section of singlewall CNTs.